After a short career as a police officer, Wheeler focused full-time on becoming a professional bodybuilder. He competed for the first time in 1983, but it was not until 1989 that he secured a first-place trophy at the NPC Mr. California Championships. He placed second at the 1993 Mr. Olympia, narrowly missing a win (something he was to repeat in 1998 and 1999). He is a 5-time Ironman Pro winner, 4-time Arnold Classic winner, and has won the France Grand Prix, South Beach Pro Invitational, Night of Champions, and Hungarian Grand Prix.