Williams announced his decision Saturday at the Ballislife All-Star Game in Cerritos, California.
"The whole time I was sitting there, I was just kind of thinking," Williams said. "We got all three phases of football sitting right in the room with all these great minds. It's an amazing thing. I'm going to keep in touch with everyone here and just try and make a difference, try to better my community, better the place where my kids live. Everyone deserves a chance to get help."