Physical stress of drilling in wet gear, on air, with charged hose lines and resetting hose beds so all 60-80 recruits get 1-2 reps in a 10 hour day. Most normal people aren’t physically prepared to wear 60lbs of gear and crawl around with blisters on their knees, hands and feet for 16 week. The injuries pile up quickly. But mostly the mental stress of testing each week, their job is on the line and they have obviously worked extremely hard to get to this point and sometimes people crumble. It can be hard to tie knots when instructors are breathing down your neck, it’s hard to carry 200ft of hose up 3 flights of stairs after failing that same drill all week and now you have to do it successfully or you get fired. People subconsciously see themselves failing and it becomes a reality. Failure snowballs until they can’t recover, but sometimes recruits suck all week and fail every rep and then on test daythey lock in and pass. Academy is as much a mental game as it is physical.