11,000 Km cycling. Not sure it is really an accomplishment nor that I'm really proud of it, matter of fact it wasn't a goal to begin with, but it happened naturally so it's all good I guess. One thing I learned is with all this time spent on a bike your mind has plenty to reflect and even to debug and mentally compile your code you struggled with before during the day. It's somehow often diffcult to totally disconnect your mind from your day job.
I've also came to really appreciate the efforts done by endurance athletes. It's so much more than just training, it's nutrition, sleep, rest, preventing injuries, so it can be mentally exhausting. Recently I remember reading the headline of an article stating that too much sport is as bad as too little on the mind, there is truth in it I think. The (relative) difficulty of this kind of endeavour is well summed up by Kipchoge: motivation + discipline = consistency.