PORT ST. LUCIE, Fla. — By the end of last season, Terry Collins admitted that he was “gassed.” Despite a season filled with tumult, he guided the Mets to a pennant, only to fall in the World Series. And it took time to turn the page on that loss.

But on the eve of the first 2016 workout for pitchers and catchers, the first real workday of spring training, Collins said he feels re-energized by the start of a season that will be loaded with expectations.

“There’s a different air in the clubhouse for sure,” he said Thursday.

Collins will preside over his 12th camp as a major-league manager. But not since his first year, in 1994 with the Astros, has he entered spring training with a roster so devoid of question marks. Position battles, a staple of spring training, will be virtually nonexistent with the Mets. But Collins still will have a laundry list of tasks to accomplish during the coming weeks.

The Mets’ title hopes will be staked to their rotation, a group that includes four of the best young pitchers in baseball: Matt Harvey, Jacob deGrom, Noah Syndergaard and Long Island’s Steven Matz. Bartolo Colon, a former Cy Young Award winner, rounds out the group.

By July, they could be even better with the return of Zack Wheeler. Once Wheeler is back, Collins left open the possibility of the Mets occasionally using a six-man rotation, a tactic they employed last season.

“If there’s a staff that can actually say they have possibly five No. 1 guys, we’ve got it,” Collins said. “We’ve got four of the best arms in baseball and a Cy Young Award winner in our rotation at the moment. It’s pretty impressive. And when Zack gets back, we’ll have another one of those possible No. 1 guys. It’s going to be really impressive to see.”

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But living up to that potential requires keeping those arms healthy. For the Mets, that means delaying their first Grapefruit League appearances by four or five days to cut down on their spring training workload.

Collins also intends to sit down with David Wright, who is entering his first full season since being diagnosed with the back condition spinal stenosis. To keep Wright healthy, limitations could be put on his practice repetitions during workouts.

“The one thing you can’t do is get yourself so fatigued that you end up breaking down,” Collins said. “Those are some things we’ve got to look at in spring training and during the season.”

Collins’ most important job during spring training could be setting the tone for a team that now faces heightened expectations.

“I want that swagger,” he said. “We’re good. We’ve got a good team. Now, we can’t be egomaniacs about it. But you’ve got to walk out there with that confidence that we’re going to win.”

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Notes & quotes: Former Mets closer Bobby Parnell signed a minor-league contract with the Tigers. The deal includes an invitation to spring training. Parnell, 31, saved 22 games for the Mets in 2013, but his career has since been stalled by a series of injuries. He missed all but one game in 2014 after undergoing Tommy John surgery. Though Parnell returned last season, his velocity did not. He posted a 6.38 ERA in 30 appearances before becoming a free agent.