LAS VEGAS -- When former welterweight/lightweight champion B.J. Penn returns to action at UFC 152 in Toronto on Sept. 22, he intends to be a lean, mean fighting machine -- literally.
Penn will enter the cage against fast-rising welterweight contender Rory MacDonald with a chip on his shoulder. It's been there ever since MacDonald called him out in June.
Accepting MacDonald's challenge was a no-brainer for Penn. A victory lets Penn settle a long-running feud with several members of the 22-year-old MacDonald's training camp.
"He thinks that I am a stepping-stone," Penn said. "He thinks this is his dream fight. But he doesn't realize that this is my dream fight.
"To beat him, to beat (his trainer) Firas (Zahabi), to beat (his mentor, welterweight champ) Georges St. Pierre and (his Montreal-based gym) TriStar Gym in Toronto in front of everybody is my dream."
Penn had the option of returning to action as a lightweight, where he arguably has found his most success. But at this point in his life, Penn reasoned that competing at 155 pounds doesn't make sense.
"I don't think it's good to keep myself down like that," Penn said. "It showed after a while."
In his last bout at lightweight, a unanimous decision loss to then-champion Frankie Edgar in August 2010, Penn appeared sluggish, especially in the later rounds.
Edgar's speed and elusiveness were too much for Penn to overcome. He returned to welterweight but found little success, going 1-1-1 during a three-fight span.
It was a lopsided unanimous decision loss to former Strikeforce welterweight champion Nick Diaz on Oct. 29 that made Penn seriously consider retirement.
While contemplating whether to fight again, Penn reflected on his career. He reasoned that he could hold his head high for the most part.
But there was one thing that still embarrasses Penn about the past -- his physical conditioning.
He looks at pictures of himself as a welterweight and drops his head, almost in shame; Penn was rarely in top shape.
Being out of shape, however, will not be an issue at UFC 152.
I want to come up to 170, 175 pounds ripped," the 33-year-old Penn said. "I want to take this belly off.
"I'm not stupid. I see every time that I'm up there fighting at 170 that I have a belly. I have to get rid of that.
"That's my fault. I want to make a push. I want to do something."