In 2017, the Celtics held training camp in Newport, R.I. The sparkling new Auerbach Center in Brighton was a year away from opening, so the trip was a way to escape the team’s rundown practice facility in the back of a Waltham health club and promote team bonding.

It was also Jayson Tatum’s rookie year, and the superstar forward can hardly believe a decade has passed since then.

“I just kind of remember it like it was yesterday,” Tatum said before Thursday’s practice. “It’s hard to imagine it’s already my 10th one. Just trying to stay present more than anything, because obviously I know how fast it’s going by. Just trying to enjoy it.”

At the time, Tatum was a shy, greenhorn prospect from Duke trying to find his way on a roster that included All-Star talents such as Kyrie Irving and Al Horford.

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Tatum has experienced so much since then. He is a four-time first-team All-NBA selection, he has his own signature sneaker — along with countless other endorsements — and he helped the Celtics win the 2024 NBA title.

Jayson Tatum took a duck boat ride through Boston as an NBA champion in 2024.Kayla Bartkowski For The Boston

But one of his most defining moments was also one he would like to forget. On May 12, 2025, he tore his Achilles in Game 4 of the conference semifinal series against the Knicks, and he wondered then if he would ever be the same.

He returned last March and showed glimpses of his All-Star form, but there were potholes to navigate. On his first dunk attempt, he was blocked by the rim because he did not have the necessary burst. After long stretches, he was much more winded than usual. And the speed of the game was initially jarring.

“I was cleared, but mentally, from a conditioning standpoint, I wasn’t myself,” Tatum said. “I think for me when I came back, it was great from a mentality standpoint to get over that hurdle of playing and even if I was at 80 percent of myself, knowing that I could still be effective.”

Throughout, Tatum said those games were part of his rehab process. And that process continued this summer, when Tatum was able to attack and truly get his swagger back and push forward without reluctance or limitation.

“Just going into the offseason knowing that I had the whole summer to get my body right and get the rhythm of playing basketball again, I feel so much more confident from a mental standpoint and physically than I did last March,” he said. “That’s how it should be. It’s a long journey from the injury I had, and I feel great.”

So, he enters his 10th NBA season with a new appreciation and a new perspective. The 28-year-old will never be an in-your-face presence with his teammates, but he understands he is now, believe it or not, one of the older veterans. He is also one of the best basketball players in the world. And he is eager to take on more responsibilities as a leader.

Tatum has said that there are different ways to lead, and he provided an example this summer, when he organized informal workouts in Los Angeles with teammates. They played basketball and golf. They shared meals and started building the cohesion they believe will help them remain an Eastern Conference force, all at Tatum’s urging.

“It had to do with the new guys on our team and with the rookies,” he said. “And, I don’t know, just trying something new. It’s kind of like the first time we’ve ever done that since I’ve been here. Getting in the gym in the summertime when we normally wouldn’t be around each other and play some golf and just hang out, just kind of build that chemistry.”

The Celtics enter training camp healthy

Celtics coach Joe Mazzulla answers questions from the media ahead of the season.

Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him @adamhimmelsbach.