Sox pitcher Jon Lester works out at the Minor League Complex yesterday in Fort Myers, Fla. Said Lester, who is recovering from lymphoma: “The doctors said, ‘Go get ’em.’ They told me to listen to my body, trust myself and just go about getting myself stronger.”

AP / Chitose Suzuki

FORT MYERS, Fla. — Jonathan Papelbon dropped off his gear yesterday, looked around the clubhouse at the Boston Red Sox’ minor league complex and did a double take.

The Red Sox right-hander thought he recognized the teammate he was looking at, but Jon Lester didn’t exactly look as Papelbon had pictured he might. And that was a good thing.

“I didn’t expect him to look that good,” said Papelbon. “It’s amazing, man, after all he went through. He looked like the same old Jonny.”

In some ways, though, Lester has changed.

For one thing, he’s just happy to be out on the field, in Red Sox attire, throwing off a mound, determined to be less hard on himself and to enjoy the game more. And while players often say they are “just happy to be here,” in Lester’s case, the phrase has significant meaning.

How could it not? Lester persevered through agonizing physical and mental trauma after being diagnosed with anaplastic large cell lymphoma last August, a diagnosis that not only shut down the left-hander after a promising rookie season in the big leagues, but also cast doubt as to how the lymphoma would affect his career.

But after six rounds of chemotherapy, the last of which was given to him at the Fred Hutchinson Cancer Center in Seattle on Dec. 21, Lester is in camp with the Sox, cancer-free and trying to prove to the Red Sox and their medical staff that he is strong enough to pick up where he left off on the mound.

Lester, only a month removed from his 23rd birthday, threw off the mound yesterday in the batting tunnels, the Sox’ unofficial workouts having moved indoors because of rain that pelted the area during the morning.

Lester has been here 10 days, trying to fine tune his mechanics in advance of the first official workout, which will come Sunday. Along the way, he has been eating whatever he wants as he builds up his weight. He was down to 190 pounds after the chemo, but he weighed in at 212 pounds yesterday, he said, only three pounds short of his playing-weight goal.

“I’m feeling good,” said Lester.

“Just getting out of the house was good. I was in kind of a bubble for a while. I mean, I went out (between chemo courses) but I had to be careful, make sure I washed my hands, make sure I wasn’t around sick people,” said Lester, who was susceptible to such things as colds, which would have set back his chemo schedule.

After the diagnosis, his goal all along had been to make it back to training camp on time and he has achieved that goal. Another goal is to prove to the Red Sox that he doesn’t need special treatment, that he is ready to compete for a spot in Boston’s season-opening rotation.

Certainly, if he had completed the 2006 season in good health, he might have been guaranteed a spot in the rotation. After going 3-4 with a 2.70 earned-run average in 11 starts for Pawtucket, Lester won his first five starts after being promoted to Boston on June 10 and wound up 7-2 with a 4.76 ERA in 15 starts before back pain and the discovery of the anaplastic large cell lymphoma ended his season after an Aug. 23 start in Anaheim.

This spring, though, he isn’t so much about being judged on his ability to get hitters out as it is about his health and his long-term career.

And Lester knows that the Sox already have said they would prefer to go slowly with Lester, the team’s first pick in the 2002 draft, especially since Boston already has Curt Schilling, Josh Beckett, Papelbon, Tim Wakefield and the expensive Japanese import, Daisuke Matsuzaka, penciled in for the rotation.

Lester, who has handled the illness and treatment with amazing maturity, said he understands the Sox’ position.

“I think it’s because they haven’t seen me yet,” said Lester. “Maybe once they see I’m in shape, I feel good, I’m running (they’ll change their minds), but I think everybody just wants to do what’s in my best interests. They’re just being cautious, so if they say I have to back off a little, I have to listen to what they say.”

Lester has been listening to doctors for about six months now. After receiving his first round of chemo at the Dana Farber center last September, he went home to the state of Washington to be with his family and doctors in Seattle, about an hour’s drive from his home in Puyallup.

The outpatient chemo sessions would last for between two and two-and-a-half hours, with Lester sleeping, or working on crossword puzzles, or watching TV or playing video games. He took the anti-nausea medicine for each round but became ill after one of the rounds. He had a CT scan, and on Dec. 1, the day of his fifth round of chemo, he was told the test had come back clean.

That’s when he knew he’d be at spring training on time.

“The doctors said, ‘Go get ’em,’ ” said Lester. “They told me to listen to my body, trust myself and just go about getting myself stronger.”

And that is what Lester has done. His hair, which had fallen out in clumps because of the chemo, is growing back slowly. His legs are getting stronger. . His pitching mechanics are improving daily.

Lester will have checkups every three months, hoping to reach the five-year, cancer-free mark that will consider him cured.

Four Boston-area college students, meanwhile, have begun selling silicone wristbands featuring the slogan “#62 Striking Out Cancer" on a website ( www.thelesterproject.com) for $6, with the proceeds going to the Jimmy Fund.

Despite all the promising medical news, Lester, who has changed his number from 62 to 31 for this season, can’t help but think of the ordeal he has gone through, though he does not dwell on it.

“Lying in bed at night, or when I’m not doing anything, I think of it a bit,” said Lester. “As long as I keep busy, I’m all right. I try not to think about it too much. I’m happy to be here. I’m enjoying life.”