This spring, he's moving around without any problems for the first time since the beginning of his senior year in 2012.
"When I had trouble in the (fall), it was with explosion," Marcell Harris said. "Now I have my explosion back, getting out of my cuts and exploding off my right knee. Everything is back."
The optimism has returned for Harris after a difficult fall. He wanted his knee back to where it was before the injury so he could get on the field and play in his first game wearing orange and blue. The difficulty of the mental side made it even tougher for him. He watched many of his good friends and teammates make impacts as freshmen, but he was bound to the training room to continue the rehab of his knee.
Harris thought he was mentally tough before the injury, but the circumstances showed him how tough he had to be.
"Coming back off that mentally, you have to be very strong," Harris said. "I kept all my faith in God. I learned from that journey to take it slow, let them work you out and make sure you do extra and beyond to get back to where you were. That's what I did and I'm back to where I was."
Being off the field gave Harris a chance to learn. At first, it was hard to watch his teammates practice and prepare for each game but soon he was realizing that it could benefit him. He watched a veteran Florida secondary every day, seeing how juniors and seniors prepared themselves on the practice field, in the weight room and in the film room.
He watched older safeties like Cody Riggs, Jaylen Watkins and current safety Jabari Gorman. Harris took mental notes in how they prepared for every opponent, wanting to emulate that when he got his chance to play.
But there's no substitute for getting on the field. That's where Harris is learning the most since he stepped on campus, as he's now healthy and going through drills without limitations this spring. Florida coach Will Muschamp, who also serves as the safeties coach during drills, note that this is the first time the Florida coaches have seen Harris play healthy since they worked him out during camp before his senior season of high school.
The results of the spring have been positive so far.
"I trust my knee 100 percent," Harris said. "Mentally, I had to get right. Physically, I feel great. I'm trying to be better than I was in high school, so just being better and working on my craft like flexibility and bending, anything I can do to help."
The timing for his return is perfect. With all the veterans on the team at safety last season, Harris likely wouldn't have made a big impact even if healthy. Now, he's battling with multiple other young safeties, trying to win one of the starting jobs.
"It's spring and everyone is showing what they can do as a player," Harris said. "Coaches are always evaluating. There's a lot of talent back there at safety. You've got veterans and us new guys that came in. We're just out there competing every day and giving it our all for Coach Muschamp."