For over 45 years an avid runner and serious cyclist. Competed from my late teens too early 30s in middle distance running 5k-half marathons, and was pretty good. 5:20 to sub 6:00 times. Back then and decades later now, when running up a steep hill or sprinting at length, I'm fairly in shape when hitting a semi-anaerobic threshold... BUT, there's like this huge anxiety thing in "my blood" and it's not psychological origins, it's physiological: I love to run and I don't dread at all challenges of steep hills or anything else. Same thing, going back decades ago too. My question is: is this somewhat common, and is it related to lactic acid and that whole anaerobic thing on the cellular level?? I definitely like to challenge myself with steep hills and some of them are half a mile long. Thanks!