By Shane Thomas

I'm sure many of us have done at least one thing in our lives that took a substantial amount of time and effort: completing a degree; moving house; or passing your driving test. And when it's done, we can relax, look back on our achievement and think, "Glad that's over. Don't fancy going through that again."

But imagine that being your whole life. Daunting challenges being the norm, rather than the exception. And not only do you accept this as your state of being; you actively embrace it.

Can you relate? No, me neither. But elite athletes can, not least the ones currently competing in Rio. And in that exclusive sphere of athletes is an even more exclusive group; sportspeople for whom once wasn't enough. They've already reached the pinnacle of their sport, and have come back for more. Why climb Everest? Because it's there. Already climbed Everest? Climb it again...

Read the rest of the piece at Media Diversified.

The Greatest Events in Sporting History" is available to download from http://www.simplysyndicated.com/shows/sportinghistory/, e-mail us at sportshistoryshow@googlemail.com and you can follow us on Twitter @TGEISH