What led to severe AF for me, was working 12 hours a day six days a week and having terrrible middle insomnia. For three years, I slept 3 hours a night max even with sleeping pills, sometimes when running some huge events, uber presssure and I was still refusing to give up my karate and adventure sports. Do a 25 mile mountain bike ride on the Sat, sleep 2 hours, then do it again on the Sunday, sleep 2 hours, and then back to work on the monday.
Lived on cigarettes, I look back now and wonder how the hell I actually managed to do it! Existed purely on adrenaline, no wonder my 'throttle' is stuck on and ive used up all my reserve tank!