Entertainment Tonight ET Online ETOnline.com

War hero and former Dancing with the Stars champ J.R. Martinez is able to smile now despite his many scars from an explosion in Iraq, but it's been a long road to regain his happiness.

RELATED: Meet J.R. Martinez's New Baby Girl!

J.R. revealed to ET's Christina McLarty that while in recovery from his horrific accident, he had 33 surgeries in 34 months. As his burns covered more than 34 percent of his body, J.R. needed to use skin grafts to cover some of the damaged areas. Doctors were forced to take extreme measures, using saline implants to expand his skin in the scalp and chest so that there would be enough to cover the worst areas.

"I never had thoughts of suicide," said J.R. when asked about his darkest moments. "But I did have plenty of thoughts of, 'I would've been better off if I wouldn't have been pulled out of the truck.'"

VIDEO: J.R. Martinez on His Horrific Accident

J.R. details his recovery in his memoir, Full of Heart, out now. The book is dedicated to his mother, who provided him with inspiration and encouragement.

"It was from her that I learned that scars aren't always on the outside, but you still smile," said J.R.

J.R. is taking his trademark smile to the New York City Marathon on Sunday where he will be running for the Timex team, raising money for charity.