There were the long days and nights, the moments of self-doubt and the bus rides without the promise of more.

Kyle MacLean is lucky to come from a hockey family, with a father who was once a Stanley Cup champion for the Devils, but that was no guarantee of his own success.

It wasn’t even a guarantee of being drafted, as he found out the hard way.

Those moments of disappointment — first when MacLean was 18, then 19, then 20 — presented three forks in the road, all in turn.

He could have taken it as a sign that this wasn’t going to work out. He could have enrolled in college, gotten a degree, had a career doing something normal.

“Everybody probably has those thoughts,” MacLean told The Post from the Islanders’ dressing room before their 5-4 season-opening overtime loss to the Utah Hockey Club. “I think, for the most part, you just gotta bury those thoughts and trust in your ability and work ethic, stay with the process.”

It was no surprise that he was in the lineup Thursday.

Since MacLean was called up last January, spending 32 games and the playoffs with the NHL club, he earned himself a spot and left no doubt.

Still, on MacLean’s first opening night with an NHL club, he was feeling a familiar mix of excitement and nerves and validation, even if he played seven games too many last season to be considered a rookie now.

“It feels good, for sure,” he said. “But I think it’s only the first step and can’t get too caught up in it. It’s a long season. I’m just happy that I had a good camp and kind of built off last year a little bit. It feels good, but definitely a long season ahead.”

At a moment when the Islanders have turned away from the Identity Line, MacLean — a bottom-six center who chases after the puck with such consistent fervor you’d think the Abominable Snowman was after him — appears to be the perfect player to embody the hard-charging, grinding hole left behind in the wake of the departures of Cal Clutterbuck and Matt Martin.

Rarely is it so clear, so fast, that a player will be a fan favorite.

“What I do appreciate about him right now is he never took anything for granted,” coach Patrick Roy said. “He came in this year, worked harder and really played well in those exhibition games. Scored goals in a lot of those exhibition games. And he’s been steady every night. That’s the consistency that you’re looking for for a guy like this.”

Indeed, MacLean still feels compelled to prove he belongs here despite having been perhaps the Islanders’ best skater in their five-game first-round loss to the Hurricanes during the playoffs.

As had been the case throughout the last week of camp, MacLean centered the fourth line against the Utah future Yetis, skating between Casey Cizikas and Oliver Wahlstrom.

There is some question as to whether Wahlstrom will stick long-term in that spot and whether MacLean will continue to take faceoffs over Cizikas, who won them at a clip nearly 10 percent better than MacLean last season — an area in which everyone acknowledges the 25-year-old needs work.

But MacLean’s game is tailored to center a fourth line, and more specifically, it might be built to center the Islanders’ fourth line.

This is what he’s used to doing, putting his head down and chipping away at perception. Maybe that’s why, presented with that fork in the road, he kept at it each time.

“You gotta have that belief that you can do it,” MacLean said. “If you lose that, it’s the wrong way to go. You always gotta keep that and just keep working and trust the process.”