ANDERSON, Ind. -- For Indianapolis Colts running back Vick Ballard, the date of his surgery -- Sept. 19, 2013 -- and the reason why he needed the procedure -- a torn ACL because of a cut during a running drill in practice -- are still entrenched in his mind like it just happened hours ago.

Ballard's second season came to an end days prior to Week 2 because of the knee injury.

"You never forget anything like that," Ballard said. "It's like a car crash. You remember the last few seconds. I remember everything. I've made the cut a million times. It was one of those things."

Ballard has put in the time to rehabilitate his knee, and he passed his physical Wednesday morning clearing him to take part in training camp. He's been cleared, but the Colts will likely keep a close eye on him during the first part of camp at least.

Ballard showed that his knee has healed when he was sprinting around the base paths during teammate Robert Mathis' charity softball game in late June. But a softball field is way different than a 300-pound defensive lineman flying at you.

One of the biggest issues with Ballard now will be overcoming the mental obstacle of returning to the field, cutting hard on his knee, getting hit in his knee and regaining the speed that allowed him to be the Colts' leading rusher in 2012.

"I'm just trying to keep my mind right," Ballard said. "It was tough physically, but physical pain goes away. You have to nurse yourself to get over any mental hurdle you have. I'm just keeping my confidence."

Ballard, who rushed for 814 yards as a rookie in 2012, is about to join a crowded backfield that also features Ahmad Bradshaw and Trent Richardson. All three will get snaps, but coach Chuck Pagano said during the offseason that they want a "work horse" in the backfield.

"All of us have carried the rock, been the primary back in big games," Ballard said. "It's going to be interesting to see how it plays out. I feel like all of us can contribute and make plays."