Bobby Portis worked out for the Boston Celtics this week and revealed a dark motivation for pregame fuel.

“I always envision someone hitting my mom,” Portis said. “That’s something I do for myself because I want to make myself mad when I get on the court. It’s all business when I step on the hardwood.”

Portis once stepped in between his mother, Tina Edwards, and an angry boyfriend as a young teen in Little Rock, Ark., and grabbed the man’s fist.

“That’s something I had to go through as a kid, my mom and domestic violence,” Portis said flatly. “I didn’t want that to happen anymore, so that’s something I’ve always envisioned.”