I've done both, i.e. endurance events (triathlons, marathons, ultras) and powerlifting/weightlifting (yes, olympic weightlifting). They are different mindsets.

I've done both, i.e. endurance events (triathlons, marathons, ultras) and powerlifting/weightlifting (yes, olympic weightlifting). They are different mindsets. Training for endurance events require a level of suffering e.g. when I did the 777 (it's a small list of people who have done it - not as small as the barkley though! - so it's easy for me to prove I've done it if anybody is skeptical), it was both mentally forcing myself to train to run 2 marathons a day, as well as the physical effort/pain (I have terrible feet). Another nightmare was the MdS, 250km in the sahara. Forcing myself to run a half marathon with a 10kg pack in the middle of day (for the heat acclimatization)... wouldn't wish that to my worst enemy. Training for powerlifting/weightlifting is a different type of suffering (I have medalled in my weight class and age group). You KNOW you can't just dump 10% on top of a PR (whether weight or rep) and "gut-it-out", the way you can gut-it-out an extra 10-20 minutes on a run/cycle/swim. I guess it's like topping out on a certain speed for a certain time, in a run. If you can run 16min 5kms, you know how hard it is to get below that, say sub 15mins. It's not "EASY" to cut your time by 10% in the 5km by just running more mileage. So it requires a different mindset, willingness to analyze, change training etc. I think both are complements. Of course, if you have only done one and not the other, it's easy to say "you should try endurance running, you'd be surprised", or "you should try to lift heavy weights, you'd be surprised". Most people will never hit that limit, and won't know what it means in terms of the effort required to try to transcend those limits. Oh, and BTW, I do mountaineering for "fun", because on the one-hand the views you get are amazing, and on the other hand, the preparation required for it is a microcosm of what, IMHO, you need to do to succeed in life - hard work, persistence, long term vision etc. And you get to do it with friends, lol (climbing stairs with a 50lb bag, what fun)