DEERFIELD, Ill. -- Taj Gibson doesn't have to explain what he focused on most during his offseason conditioning -- the evidence is etched into his bulked up 240-pound frame. The veteran forward said that he added 15 pounds of muscle over the last few months and feels like a different player on the floor.

"I think I bulked up a little bit more," Gibson said after Sunday's first practice. "Being in the playoffs the last couple years, it gets more and more physical. I put on a ton of weight. Mostly I went out (to California) and just lifted, worked out with Derrick (Rose). I'm 240 (pounds) now. Just trying to build confidence -- it's coming. I know the plays, I know the offense, I know players' strong suits. Once you get confidence in this league, you can take off. It's all about confidence."

Having confidence is a mantra that Gibson is focusing on. He wanted to add some more muscle to his lanky frame but he admitted that Bulls head coach Tom Thibodeau was a little concerned at first about just how much mass the USC alum was adding.

"He was a little bit worried about my weight because he didn't want me to get kind of fat," Gibson said. "But he wanted me to be lean, more muscle, and it's been great."

After struggling last season with the pressure that came with signing a big contract extension, Gibson looks more confident on the floor and is talking like a man who wants to take the next step in his development. Aside from the added bulk, Gibson has been working on a 3-point shot that he wants to add to his repertoire this season.

"The coaches want me to do it," Gibson said. "Even Derrick (Rose) wanted me to shoot it. It's all about confidence. The one thing I notice is when you bulk up things tend to get a little easier but I haven't shied away from it. Right now I'm just focused on what things I can do to help the team and how to find my niche here and there."

Gibson is also focused on maintaining the good health he has heading into camp. He had to miss the Team USA mini-camp in Las Vegas in July after badly spraining his right ankle.

Gibson admitted that the ankle injury put him out for several weeks in late July-early August and he spent time with the Bulls' new director of sports performance, Jen Swanson, in order to get it ready for training camp. It was because of that therapy, and a cortisone shot, that Gibson feels confident he is ready to roll after a tough summer.

"That shot, it was real painful," Gibson said. "I didn't really expect the shot to be so painful. But they said it would take some time and everything's OK right now."