Through a vigorous regimen of boxing, hills and running, Lewis has shed nearly 20 pounds since minicamp to report to McDaniel College at 240 pounds.
His body-fat percentage and overall health have improved to the point that Lewis, 23, is reminiscing about his early college days at Tennessee when he was the leading freshman rusher in the nation.
"Yeah, I feel quicker," Lewis said. "I feel much faster. My weight is down a lot. My body fat is down a lot. So, I feel like I'm back to the old Jamal. Not 'rookie year Jamal' but 'college Jamal.'"
That version of Lewis was the one without surgeries on both knees, including one after an injury to his right knee that cost him his sophomore season with the Volunteers.
Now, Lewis has recovered well again after previously rehabilitating his right knee well enough to leave school after his junior season and be drafted fifth overall three years ago. Lewis managed to rush for 1,327 yards and six touchdowns last season despite question marks about how well he would recover from the surgery on his left knee.
Still, Lewis lacked the consistent element of breakaway speed and his endurance wasn't ideal. The knee simply wouldn't allow him to do all that his mind envisioned.
The operative theory in sports is that an athlete isn't truly 100 percent until the second year after a knee injury.
"It's amazing to watch Jamal's opening week of practice, how he carried himself, the quickness, the speed," Ravens coach Brian Billick said. "Compared to where he is today, keeping in mind that he had a pretty good year, it's exciting to think about what a good year he might have."
"It surprised me how early he looked good last year and anyone could see he got stronger as the year went on. There is some legitimacy to the two-year process, and the way he looks right now he's going to have a great year."
Reckless abandon defines Lewis' running style, simultaneously a hindrance and an advantage. Occasionally, Lewis leaves himself open for fumbles while stretching for extra yardage or vicious tackles when his timing is off on leaps toward the end zone.
During practice Tuesday morning, Lewis was nailed a few times on aborted leaps to the goal line. Once, linebacker Bart Scott nailed him at the apex of his jump. Another time, cornerback Chris McAlister plowed into him after his initial charge was stopped.
The hits didn't faze Lewis, though.
"He likes to go up and over," Billick said. "He scares the hell out of me every time he does it." Last season, Lewis fumbled eight times, losing seven. For his career, he has 14 fumbles with nine lost.
Still, Lewis finished sixth in the AFC in rushing last season while establishing a career-high with 47 receptions for 443 yards and one touchdown. The major difference in Lewis was not always finishing off his runs.
Traditionally, Lewis' top seasons have come when he's in optimum condition. He's banking on that not being a mere coincidence.
"With me, it's been one year on, one year off, one year halfway," Lewis said. "It's kind of like the beginning of my career in the league and the beginning of my career in college. Those have pretty much been my best years, my most conditioned years."
With the Ravens' quarterback situation remaining unsettled, it's a fair bet that the Ravens' offensive style will be centered heavily around Lewis' bruising running and Pro Bowl tight end Todd Heap.
When the Ravens won the Super Bowl in Lewis' rookie season, he set a club record with 1,364 yards rushing and the team ranked fifth in the league in rushing offense.
"We're going to have the nasty attitude of, 'Just go out there and hit them in the mouth," fullback Alan Ricard said. "With Zeus, the rest of the guys, me and Jamal, we look forward to being the bullies."
That's right up Lewis' alley.
Lewis spent all those countless hours down in his hometown of Atlanta pounding punching bags. Now, he wants to inflict some punishment on the football field.
"We've got to be confident and manhandle some of these defenses," Lewis said. "I'm excited about this year."
NOTE: The Ravens continued their tradition of hazing rookies who hold out.
Rookie quarterback Kyle Boller's brand new Cadillac Escalade sports utility vehicle was towed past him while he conducted a live television interview.
It was later returned to him, though.
Aaron Wilson writes for the Carroll County Times.