It's safe to assume that if you're considering an IRONMAN, you've done a triathlon before (if not, you should). But even if you've finished a 70.3 race, the transition to 140.6 is substantial. The countless hours in the pool, on the bike and on the trails will catapult you into a new echelon of fitness, where a half marathon is just another casual training day. You'll shed pounds, probably get a tan and overall just feel fit. Plus, not only will you gain a ton of stamina, you'll be more positive, too.