He can point to a lot of sources in diagnosing his lost season.

He was thinking too much, living inside his head. He was craning his neck to the future, wondering when a promotion would come. The thoughts wouldn’t leave him on the mound, and suddenly, his windup needed tinkering. He was 1,000 miles from home, and his family wasn’t around anymore.

But then, maybe Justin Dunn doesn’t have to contemplate his 2017. Maybe not thinking about it — or thinking at all, really — is the solution.

“That’s one of the things that screwed me up for last year,” the Mets pitching prospect said over the phone this week. “I was trying to make things happen way too fast. I feel I can do a lot of things that are undoable. I put a lot of pressure on myself. I put more and more pressure and kept thinking about it.

“This year I’m just going about my business every day. Cut down on walks as soon as possible, that was something that plagued me this year. Fill up the zone and attack.”

So that’s what he has done.

The 22-year-old right-hander, the Mets’ first-round pick out of Boston College in 2016, has begun to reclaim his status as one of the organization’s top prospects to begin this season. With High-A St. Lucie, Dunn has allowed two earned runs in 14 ¹/₃ innings, striking out 19 in that span. The control issues haven’t completely left him — he has walked six in the early going — but a season after the 19th-overall pick put up a 5.00 ERA in 95 ¹/₃ innings with St. Lucie, this small sample size qualifies as encouraging.

With a mid-90s fastball, quality slider and developing curveball and changeup, the Freeport, L.I., native, who was the ace of Boston College’s staff, was the prize of the Mets’ 2016 draft. The question appeared to be whether a 6-foot-2, 185-pound string bean could survive in the rotation or whether he was better built for the bullpen, but his arm wasn’t in doubt.

After the draft, the Mets assigned him to short-season Brooklyn, where he allowed five earned runs in 30 innings (1.50 ERA) and struck out 35.

“I live 45 minutes from there,” Dunn said of Brooklyn. “My family’s at every game.

“[Not seeing them] was definitely part of it,” he said of his 2017 season. “I didn’t see them as much as I did before.”

Last year was a slog at St. Lucie, where the Mets tried various remedies — shutting him down, bringing him out of the bullpen — to right Dunn, who said he hasn’t had an experience like that since 2014, when he was an 18-year-old freshman trying to find his way at Boston College. Now he thinks his thinking is to blame.

It’s easier to recognize than rectify.

Dunn said he’s keeping a journal, as directed by St. Lucie mental skills coach Sabrina Gomez, in which he writes down what he thinks about and when. Yes, he’s also keeping tabs on hitter scouting reports and which pitches work on whom, but after his outings, he chronicles his frame of mind, too.

“I try to figure out when I wasn’t mentally in the game,” said Dunn, ranked by MLB.com as the team’s third-best prospect. “I was thinking this during the pitch, as opposed to two weeks I was thinking that. And when I was thinking this, I pitched better.”

Notably not on his mind — at least ideally for him — is what happens next. Continuing to flourish would mean a promotion eventually to Double-A Binghamton, closer to home and closer to his end goal: Citi Field.

It’s a goal that can feel as distant as New York and Florida, and one he tries not to let control him, as alluring as it sounds.

“It’d mean everything,” Dunn said of the thought of suiting up in Queens. “To have myself playing 15 to 20 minutes from home. Having my entire family as well as every single friend there … to have the potential to help the franchise win and bring championships there.”

It’s nice, but dangerous, to think about.