United States paracyclist Scott Martin is a man accustomed to risking his life and he will do so again in the quest for medals at the Paralympic Games in Rio.
The 34-year-old, a decorated former Marine, suffered brain injuries caused by improvised explosive devices on two separate occasions while on duty in Iraq.
As a result of the damage, he temporarily lost the ability to read and walk.
Encouraged to remain active during his rehabilitation, Martin disregarded medical advice to become one of his country's leading Paralympic cyclists.
"I had a lot of grade-three concussions which are the highest and they said I couldn't stay in combat as if another one happened then it was a good chance it could kill me," he said.
"I had gained weight at the hospital and the doctors wanted me to get back into sports, but they said do anything but don't ride a bike. Tell me not to do something and that's exactly what I'm going to do.
"They were saying if you fall off the bike you could hit your head so there was a good chance it could cause permanent damage or even death, but there is a risk in everything in life and you've got to enjoy yourself. I enjoy cycling so I take the risk."
According to Martin, the effects of his injuries present unique challenges when competing.
"I went through real bad depression and it was a year and a half, almost two years, before I started exercising again through sports," he said.
"I tried triathlon a bit, then got started with Paralympics and found cycling was a lot better for me. I just enjoyed it mentally and physically. It became more of a team thing, like the marine corps was.
"I still have a bit of slight paralysis down the right side and can have balance issues. Even on the track, riding like half-way up the banking, if there is a little bit of wind I find it harder to control the bike than others.
"After workouts the left side of the body is trashed and the right side feels almost fine as it's not working that hard.
"I'll get headaches and migraines and I'll sometimes walk into walls. I'll see them but sometimes I don't get out of the way. You get used to it, make light and have fun with it."