If he doesn't do both, the former second-round draft pick could be looking for another place to play.
Barnes, the 52nd selection in the 2005 draft, is competing with talented youngster Richard Collier for a starting spot. Given his off-field troubles, inconsistent play and contract status, Barnes realizes this could be his final chance to turn things around.
"It's kind of a big year," said Barnes, entering the final season of a four-year deal. "I would like to stay here, but that's not entirely up to me. Maybe I'll be here, maybe I won't. I don't know how exactly everybody's feeling about me staying here. Who knows?"
Although Barnes has looked solid at times, he's also been beaten for costly sacks, flagged for silly penalties and benched for poor play.
Even on Jacksonville's biggest play of the season - David Garrard's 32-yard run on fourth down at Pittsburgh in the playoffs - Barnes could have been called for holding James Harrison (the NFL acknowledged the missed call at the league meetings in March).
"I can't recall," Barnes said with a smile. "It's too long ago. I didn't see no flags. I don't remember all that. I don't remember too far back."
Despite the memory loss, Barnes dedicated the offseason to working on his speed, strength, timing and footwork - essential tools at his position - and vowed to be more consistent.
"Why can't you play good all 16 games as opposed to playing good five and then having one where you slip up and then playing good three or four and then having one where you slip you?" Barnes said. "Have all 16 good and have all the playoffs good. That's what I'm striving for."
The 6-foot-5, 325-pound lineman was arrested on drunk driving charges in November 2006. According to police, Barnes was driving 101 mph before he failed a field-sobriety test. Moments after he was handcuffed, police said Barnes unleashed a profanity-laced rant in which he called officers racist and Jacksonville a hick town.
He later apologized and pleaded no contest to the charge. He was sentenced to probation, ordered to perform community service and given limited driving privileges.
While on probation in 2007, though, Barnes drove through a yard, crashed into a tree and then left the accident scene.
Barnes initially called police and said he wrecked after falling asleep while driving to a mandatory treatment session. Four hours later, after police arrived at the scene and found Barnes gone, the player called back to report his car stolen.
When an officer told Barnes he had listened to the original 911 call, the player decided to stick with his original story.
He was cited for careless driving. He also was charged with violating a provision of his probation that limited his driving to work purposes. But a judge later ruled that Barnes didn't commit any criminal or technical violations of his probation.
The decision kept Barnes from facing jail time, but it did little to change his image.
"You realize that the things that can happen to you actually do, and that's when you realize this is serious, this is real," Barnes said. "If you have a good job and you want to protect it, you have to stay on top of those things.
"It's all about being a man, growing up, taking responsibility for things you did in the past and learning from them and making sure you don't repeat those types of things and change your whole demeanor around. Hopefully, I think things will turn around, which they kind of are right now."
"Can we trust you? Can the line trust you? Can the team trust you?" offensive line coach Andy Heck said. "We're all striving for more consistency, and if Khalif has identified that as one thing for him to work on, then I think he's right on."