OAKLAND, Calif. — Andre Ward decided to end his career on top.

Ward announced Thursday he is retiring from boxing because he no longer has the desire to fight, leaving the sport at age 33 with an undefeated record and the light heavyweight championship.

Ward released a statement on his website titled “Mission Accomplished “thanking those who helped him throughout his career and explaining his reasons for his retirement.

“I want to be clear – I am leaving because my body can no longer put up with the rigors of the sport and therefore my desire to fight is no longer there,” he wrote. “If I cannot give my family, my team, and the fans everything that I have, then I should no longer be fighting.”

Ward is currently rated the best “pound for pound” boxer by Ring magazine. But in an interview with ESPN’s First Take, he said he no longer wants to do the work leading to his bouts.

“People see what I do fight night, they see under the lights, but they don’t see the toil, they don’t see the grind, they don’t see just the pain, the physical pain that you go through, not just in the fights, but to prepare and to get ready for those battles,” he said.

“I felt the physicality of the sport, not just in the ring stuff, but the training and the preparation, start to take its toll on me for the last two or three years, and I bit down and continued to push through and at this point, it’s time and I know it’s time.”

Ward declined other interview requests through his publicist, saying he wanted to celebrate with family and friends.

Ward won all 32 of his fights with 16 knockouts. He won the Olympic gold medal as a light heavyweight in 2004.

Ward won the WBA super middleweight title in 2009 when he beat Mikkel Kessler and unified that title in 2011 when he beat Carl Froch in the Super Six super middleweight tourney final.

Ward then contended with shoulder problems that kept him out of the ring and later went 19 months without a fight because of a legal dispute with his former promoter, the late Dan Goosen.

Ward got back in the ring in June 2015, then won the light heavyweight title against Sergey Kovalev in November 2016.