Before coming to the WWE he won several NCAA wrestling titles in college and competed professionally for the first time in 2001 in WWE's minor leagues.
Brock Lesnar debuted in the WWE in April of 2002 and quickly showed his strength attacking the Hardy Boyz. He came to be associated with Paul Heyman as his agent. In June 2002 he won the King of the Ring by defeating Rob Van Dam in the finals, thus garnering him a shot at The Rock's WWE Heavyweight Championship at Summerslam. He won the title that night and it looks like he will have an even bigger future than his first four months in the WWE. He won the Royal Rumble in 2003 and went to WrestleMania XIX and won the Smackdown! championship.
He had great success in 2003, but he decided to leave the sport of wrestling, even though he only had a short career there. He supposedly is going to join the NFL.