The fitness expert and former GMTV personality dislocated his knee during a trial run of the show.
Mr Motivator, whose real name is Derrick Evans, will need to undergo surgery to correct the damage done to his knee.
Evans said that he was "devastated" not to be able to continue in what he describes as an "amazing experience".
"A heartfelt thanks goes to all the team but especially my gymnastics partner Kerry and coach Alberto, who have been so supportive and brilliant to work with - I'm sorry our journey has been broken this way," he added.
Former Blue Peter presenter Peter Duncan will replace Evans, it has been reported.
BBC recently released the first cast photo for its upcoming primetime show.
Contestants include Sugababes singer Amelle Berrabah, EastEnders star John Partridge, and Girls Aloud member Sarah Harding.