Answer by taking a quote from the following article:

Brock Edward Lesnar was born on July 12, 1977 in Webster, South Dakota, the son of Stephanie and Richard Lesnar, and grew up on his parents' dairy farm in Webster. He is of German descent. He has two older brothers, Troy and Chad, and a younger sister, Brandi. At age 17, Lesnar joined the Army National Guard, where he was assigned to an office job after his red-green colorblindness was deemed hazardous to his desire to work with explosives.

After his match at WrestleMania XX in March 2004, Lesnar sidelined his career in WWE to pursue a career in the National Football League (NFL) despite not playing American football since high school. The WWE issued this statement on their official website, WWE.com, following his departure:  Brock Lesnar has made a personal decision to put his WWE career on hold to prepare to tryout for the National Football League this season. Brock has wrestled his entire professional career in the WWE and we are proud of his accomplishments and wish him the best in his new endeavor.  Lesnar later told a Minnesota radio show that he had "three wonderful years" in WWE, but had grown unhappy and always wanted to play professional football, adding that he did not want to be 40 years old and wondering if he could have "made it" in football. In an interview about the NFL, he stated:  This is no load of bull; it's no WWE stunt. I am dead serious about this. I ain't afraid of anything and I ain't afraid of anybody. I've been an underdog in athletics since I was five. I got zero college offers for wrestling. Now people say I can't play football, that it's a joke. I say I can. I'm as good an athlete as a lot of guys in the NFL, if not better. I've always had to fight for everything. I wasn't the best technician in amateur wrestling but I was strong, had great conditioning, and a hard head. Nobody could break me. As long as I have that, I don't give a damn what anybody else thinks.  Lesnar had a great showing at the NFL Combine, but on April 17 a minivan collided with his motorbike and he suffered a broken jaw and left hand, a bruised pelvis and a pulled groin. Several NFL teams expressed interest in watching Lesnar work out. The Minnesota Vikings worked out Lesnar on June 11, but he was hampered by the groin injury suffered in the April motorcycle accident. On July 24 it was reported that he was nearly recovered from his groin injury. He signed with the Vikings on July 27 and played in several preseason games for the team. He was released by the Vikings on August 30. Lesnar received an invitation to play as a representative for the Vikings in NFL Europa, but declined due to his desire to stay in the United States with his family. He had several football cards produced of him during his time with the Vikings.

Was he ever able to play again?
The Minnesota Vikings worked out Lesnar on June 11, but he was hampered by the groin injury suffered in the April motorcycle accident.