PORT ST. LUCIE — Matt Harvey tried to hold himself back on Monday. He really did.

On his first day back as a Mets pitcher in a regular pre-camp workout, 10 days before the start of spring training, there were no proclamations about shutting down opponents.

The confidence level is still high for the Dark Knight, make no mistake about that, but after missing an entire season following Tommy John surgery, this 2.0 version of Matt Harvey was a bit different. And that is a good thing.

He knows it can all go away in an instant. This Matt Harvey was a bit humbler, a bit more in control of his words, knowing there are still many hurdles to clear. All that bodes well for the Mets.

One thing hasn’t changed though: He’s still the alpha dog.

When asked if he has any doubts he can be the pitcher he once was, the big right arm who took New York by storm, Harvey said: “As far as performance goes, I don’t think so, my mind-set is the same. I’m going to attack hitters like I always do. It’s going to stay the same.’’

And this.

“My goal is to be ready for Opening Day, regardless what is decided, that’s not up to me. Now it’s about getting used to facing hitters again and competing.’’

He is ready to rock and roll, and that’s all you can ask at this point.

“There is a scar there, but as far as moving forward, when I throw and when I work out, there are no hesitations,’’ Harvey said. “I’m not worried about anything at this point.’’

Harvey was in a small workout group that included Jacob deGrom and Zack Wheeler, and it was clear he remains the center of attention. Harvey commands attention in everything he does, whether it’s something as simple as playing catch or doing PFP (pitchers’ fielding practice) drills, like he did Monday.

Harvey turns 26 next month while deGrom is 26 and Wheeler is 25. Those three young guns can carry the Mets a long way if they can stay healthy, which was the big takeaway from Monday. DeGrom had his Tommy John surgery in 2010 and is proof of the success that can be in Harvey’s future.

“It’s fun to be part of the crew again,’’ Harvey said.

Watching those three work together offers a glimpse of what 2015 can be, and also a look back into the Mets’ long ago successful past, when their young pitchers ruled the day.

Having to face those three young power arms is not going to be easy for any opponents.

Harvey is not taking anything for granted anymore.

In the end, all this will make him that much more dangerous as a pitcher.

“Coming down here, it doesn’t feel like I missed the whole year,’’ he said. “I’ve done quite a few [bullpen sessions] and everything feels great, feels strong.

“Looking back on it, I think everybody made the right decision,’’ Harvey said of not pitching late last year. “I’m in a good place right now.’’

He has also done his homework, talking to some pitchers who have successfully returned from Tommy John surgery. He did not talk to ones who did not. No need for negative thoughts to creep into his head.

“I’m pretty on-point with my accuracy right now, which is surprising,’’ Harvey said matter-of-factly.

“Hearing from some guys [who have had the surgery and are still pitching], that is sometimes the last thing that comes.

“With this process you don’t look at the negative.”

That is all part of the plan.

“I’m going off how I feel and how the ball is coming out for me, and that process has been very successful,’’ Harvey said.

“I couldn’t be happier with the way things feels and the way things are coming out. I’m just excited to be here and be with the guys.

“I’m preparing for a normal spring training, which is nice. I’m happy to get started.’’

Matt Harvey is back where he feels most at home, a bit wiser along the way.