Globalti
Squire
I've never been particularly athletic, I've always gone climbing and mountaineering but it's possible to do those sports and not be specially fit. After childhood and teenage cycling I got into motorbikes, which are terrible for keeping you fit as you can park even closer to your destination. It wasn't until I was 33 that I rediscovered cycling through mountain biking and got reasonably fit and then 53 when I discovered road riding and got what I would call properly fit. My cycling pal on the other hand has been a roadie since college and all through his working life so has built up a long term strength and resistance to injury. As Colin points out, the harder you push yourself the closer you come to injury and I know that I'm close to that point as I have had mild chronic Baker's cysts behind my knees for three years now, which is a well-known overuse injury in cyclists and runners.
That's probably why.