He�*s no stranger to challenges. from riding 3,000 miles on his hand—powered bike, to winning medals at the invictus games. breathe, focus. his trainer, also a former royal marine, has created exercises tailor—made for mark�*s abilities. he's got no quads, no hamstrings, no calf, so he's relying off basically one muscle group, which is his glutes. and most human beings are pretty lazy with the glutes, and most of us don't actually activate them when we're doing a lot of exercise. it's incredible, really. the fact of the matter is that i think, mentally, more than anything, is where mar...