Vex King is the epitome of a very modern success story. 

The 35-year-old has overcome poverty and the loss of his father through the power of hashtags and tweets, building a multimillion-pound fortune out of positive thinking and becoming one of the country's foremost self-help gurus. 

It is a success that has led to him amassing over a million followers on Instagram and Twitter, as well as a bestselling book, Good Vibes, Good Life (fans of which include radio presenter Chris Evans and Stranger Things' Millie Bobby Brown) that sat at the number-one spot in the charts for 123 weeks and has sold more than a million copies. 

It also led to him meeting his wife, Kaushal Modha, 34, a YouTube beauty influencer with more than two million followers. I meet the couple in a smart London photography studio where they are on time, well-spoken with lovely manners and perfect teeth. 

King is quiet and gentle but not shy, Modha's skin is so luminous I make a note to start following her beauty recommendations. King and Modha both attended the same school – Abington Vale in Northampton – but didn't get together until they had left, meeting on a night out in 2009 via mutual friends. 

'After that night we started chatting every day and it felt so simple and natural,' says Modha. Falling in love with Modha was the light at the end of a dark tunnel for King. 

Born in 1987 in Northampton to Indian parents, he had a difficult start in life. When he was six months old his father died from tuberculosis and his mother, Rene, was left to bring up him and his two sisters, then aged two and four. 

'Like a lot of British Asians at the time, my parents owned a corner shop, but even when my father was alive they were just holding it together. After he passed away, my mum and my dad's brother tried to keep the business going, but it went bankrupt.' 

The uncle was a volatile man. King recalls frightening arguments and violence. 'I remember my mum sitting on the sofa and crying, then my sisters and me crying, too. I had no idea why or what was going on, but I remember feeling so angry and thinking, 'Why is life like this?'' 

As King talks, Modha sits close by, murmuring support. After the business went bankrupt, the family was homeless for three years, staying with family members then in temporary accommodation. 

Tea or coffee?

Modha: matcha

King: hot chocolate

Shower or bath?

M & K: shower

Cat or dog?

M & K: dog

Indoor or outdoor?

M & K: outdoor

Summer or winter?

M & K: summer

Night owl or early bird?

M: early bird

K: night owl

Sun or shade?

M & K: sun

Bach or Beatles?

M: Beatles

K: Bach

Book or podcast?

M & K: book

WhatsApp or phone call?

M: phone call

K: WhatsApp

King remembers one hostel being especially bleak: 'There was screaming in the night, there was often blood on the floor, smashed glass everywhere. People were hanging around doing drugs.' 

The family was eventually assigned a council house just in time for King to start school. 'Compared with where we had been living, it was paradise,' he says. King's mother worked multiple jobs to keep the family fed, but money was always tight. 

'All my life, I have seen my mother hustle for work in order to keep us afloat,' he says. 'As a child I saw horrific things. There was pain everywhere.' 

Despite this, he did well at school, then studied business information systems at Nottingham Trent University. While there he discovered the book that would change his life: Think and Grow Rich. 

Written in 1937 by Napoleon Hill, it studies the psychology of wealthy people. 'It explains that successful entrepreneurs all have a positive mindset. At that time almost every problem I had encountered was down to a lack of money. So I thought, 'OK, I need to be rich.''

He applied this new positive thinking strategy to everything he did. Initially he dabbled in music production – working with the hip-hop band So Solid Crew. It was at this time he assumed the name 'Vex King'. (He keeps his real name a secret, used only by close friends and family.) 

'I adopted it because I used to feel so angry and vexed at the world.' The money didn't start flowing in immediately but for the first time in King's life things started looking up, so he took to preaching his message of positivity to friends. 

Then, aged 20, a bad breakup brought it all tumbling down. The end of the relationship hit him hard and he spiralled into depression. 

'I felt like I was a failure. I was never going to solve my mum's money worries. Things I had been suppressing for years came bubbling back up. I was scared and uncertain, which was how I used to feel as a child.' 

He sank so low that he tried to take his own life. When he didn't succeed, King started to wonder if there was a deeper meaning to his survival. 

'I'm not religious, even though I am drawn to spiritual concepts. But after [the suicide attempt] I concluded that I must still be here for a reason. What if I was put here to spread a message of positivity?' 

Then along came Modha. 'She stunned me with her strong values and how down to earth she was.' Buttressed by his new relationship, a steady job as a systems analyst for a transport company and his belief that he had to make something of this second chance, King pondered what to do next. 

 Like so many of his generation, his thoughts turned to social media. King hit on the simple but buzzy hashtag #goodvibes and went about communicating it on Twitter and Instagram, posting positivity messages several times a day. 

He avoided what those in the self-help industry term 'toxic positivity' – which is where difficult feelings are dismissed with platitudes such as 'you got this', ie, get on with it. Which can make everything worse. 

King would post advice such as, 'The best thing you can do for everyone around you is to love yourself unconditionally,' or 'a memory that causes suffering is worth letting go of'. 

The accounts grew fast, reaching 200,000 followers within months. Earnest self-help phrases like this invite cynicism and at times, I confess, I don't understand what King is talking about. 

But his advice is heartfelt and speaks deeply to people who need this sort of life guidance. The concept of 'good vibrations' is not new. It's based on the idea that human energy is made up of vibrations and the higher the vibrations, the more positive you become and the more able you are to invite good things into your life. 

'I'm not the first person to use the phrase 'good vibes',' says King, 'but I'm happy to say I popularised it for a new generation.' It's easy to be sceptical about the power of 'good vibes' to transform a life, but what happened to King next is hard to dismiss. 

After practising his new positive mindset for only a few months, on his daily work commute he was approached by an elderly woman he'd never met before. 

'She just started talking to me. She seemed pleasant. She was small and wearing a headscarf. I wanted to be polite so I listened. She told me about my past life and that I was here to make a difference in the world,' he says. 

'She said my purpose was to share a higher message that would help people. I was sceptical but then she called me by my real name and there was no way she could have known it. I was shaken. I remember texting Kaushal to tell her.' 

And so, at just 27, King decided to listen to the messages the universe was sending him and quit his job in order to devote himself to spreading the message of 'good vibes'. 

'I would strongly advise anyone looking to change career to make sure they have the financial stability to do it. I certainly didn't,' he laughs. 'I think at the time I was making maybe £2 a month from Google ads.' 

It helped that Modha's career as a beauty influencer was skyrocketing and she could support them both. King devoted himself to the study of online marketing and gradually made it work financially. 

Well-known sportsmen (King is too discreet to name them) approached him by direct message on Instagram to ask for one-to-one coaching. 

'The first person I helped was a basketball player. He was really down and had been demoted due to an injury. All [the coaching] did was help him see himself as a whole person. I didn't know exactly what I was doing, but I did know that self-care needed to be his priority, so we worked on that. He became the most valuable player on his team and was taken on by another basketball league. He felt like I had changed his life – and he told everyone.' 

King became a word-of-mouth hit with stressed sportsmen; in a TV interview the England footballer Jesse Lingard called him an inspiration. It was Modha who encouraged King to capitalise on this new success so he started writing what would become Good Vibes, Good Life. 

The process of getting it published was, he says, arduous. 'I had to do about ten rewrites before it was even shown to publishers,' he says. 'Then so many said 'no thanks': I wasn't famous enough. I just thought, 'But the book is good.'' 

Finally he was taken on by the publisher Hay House and Good Vibes, Good Life became an instant hit. Two things brought the reality of his success home to King. 

The first was when he was in a bookshop on holiday in Bali and someone recommended his own book to him. The second was when he paid off his mother's mortgage and debts. 

'That was a profound moment,' he says. 'Releasing my mother from her financial worries was liberating. It made me feel like I had done something big and impactful.' There are a thousand positive-thinking preachers out there – what does King have that they don't? 

'I would never say I am a technically gifted writer,' he says, 'but I make people feel seen and heard. I talk about real things and real situations. I try to make things relatable by applying the wisdom I have learnt and keeping it simple.' 

He does this by stating facts boldly and concisely, such as 'a relationship isn't an invitation to change another person' or by encouraging his followers to 'spend less time with those who are emotionally exhausting and are committed to muting or misunderstanding you'. 

For me, what sets King apart – and what surely aided his early success – is his intense vulnerability. 'Wellness' preachers I have met often seem venal in real life, but King appears authentic in his mission to change lives. 

People can see he is managing his own fragility born from his rocky start in life – and being living proof that something works is very compelling. His new book, Closer to Love, examines the roots of lasting love and builds on King's fundamental idea of self-love with the theory that in order for love to last you have to be in a good relationship with yourself. 

'Good relationships come down to the acronym Rich: respect, intimacy, communication, honesty,' he tells me.  

Modha adds: 'I've learnt two important things about marriage. The first is to understand the ways in which you give and receive love, because they might be different. For example, if Vex needs time alone to process something I know it will make me feel abandoned. But I realise that he needs to be treated in a certain way. Second, I think the importance of space in a relationship is overlooked. Wanting time for yourself doesn't mean you're pushing the other person away.' 

The central ethos of the book is not ground-breaking and it occasionally delves into flowery wellness-speak, but it makes solid points. For example, King believes that the audience he is speaking to has a unique problem due to social media and dating apps – they have made relationships disposable.

'If you encounter a problem you can just swipe someone away and move on to the next person,' he says. 'It's a lot easier to walk away than to stay and make an effort to resolve any issues. People are also being trained not to live in the moment, because they can always escape it via a screen.'

His relationship with Modha is the inspiration for the book. 'No relationship is perfect,' he says. 'We are used to Hollywood love stories and it's not how relationships work. The key to a balanced relationship is the actions that you take when things are hard.' 

Parents in long-term relationships might find less in this book, as children put unique pressures on any partnership. But don't expect a tome on that from King any time soon, as he and Modha have chosen not to start a family. 

'When we told our mums, they didn't believe we meant it. It's a big thing in our community; we're expected to have children,' says King. 'But we understand what it means to be a parent and it's not a life for us. We want to travel and do more in our respective fields.' 

The couple lived apart until they were married. The wedding, in Mexico in 2018, was, Modha insists, a modest affair compared with most Indian weddings. Now they live quietly with their toy poodle Tupac in Northampton, but are considering a move to London. 

Their wellness brand The Rising Circle, which offers community and guided meditation, is still in its infancy. There's also a joint podcast in the offing, more books and their social media brands. 

'I believe things happen as they are supposed to,' says King. 'I just need to end the day able to sleep easy, knowing that I did my best and made good choices.

'No relationship is a waste'

In fact, bad ones are – in their own way – good, says King, as 'They teach you about what you do and don't want' and 'can remind you that you deserve better'. So, don't obsess over dreadful exes: 'Let go.' Besides, 'a bad relationship can be the catalyst for a journey inward'.

'True love is a myth' The trouble with 'true love', says King, is that it makes us think that when we find it all our problems will vanish. 'I wish it were that simple.' It's rather a lot to expect one person to fix all our worries and fulfill all our dreams. 'How would you feel if your partner expected that from you? Intimidated? Pressurised? Overwhelmed? Uncomfortable? Responsible?' (Yes, to all of the above.)

'You're bound to go toe-to-toe' Arguing is inevitable – so do it well. Good arguments, King explains, are likely to involve 'compromising', 'agreeing to your partner's perspectives', or – gulp – 'apologising'. These things aren't easy and you need 'a heart capable' of doing them. So no ego or pride. 'Remember, in conflict, it's you two against the problem, not against each other.'

'Love is a verb' The early rush of a relationship is great, King says, but it can't last for ever. Seriously, it's in our biology: 'physiologically speaking, humans are not designed to stay in a heightened state'. A good long partnership requires constant work. That doesn't mean you need to 'bend over backwards to keep your partner happy', but it does mean putting them 'in the front of your mind' – every day. 'Love is in the doing, not the feeling.'

'We can't get close to others if we're not close to ourselves' It's a cliché, but true, and 'the first relationship you must honour and nurture is the one with yourself'. To keep self-love levels high, King suggests writing a diary, doing hobbies, exercising. 'Recognising you're already whole will make you a better half'. Win-win.

King's book Closer to Love will be published by Pan Macmillan on 13 February, £16.99*