Today I was going through 10 or so machines doing the 60 second work and 30 second rest thing where you try to see how many reps you can get one. I've been doing his once a week for a couple of months now and trying to increase the weights on the machines, I'm up to 55 pounds on most of them now. Today I freaked my son out a bit who comes to the gym with me because I pushed myself too hard and had to sit and rest at the end because I was completely exhausted. Exhausted to the point where I wasn't finishing the walk to the car - I needed to rest and put my head a table and for 5 minutes. I I've had this happen before when I did too many lunges and basically ended up laying down for 5-8 minutes until recovering. I'm late 40s now, but this happened to me a couple of times when I was younger too (teens). It seems to be all about pushing too hard. Anybody else run into this? Do I just need to go a bit easier?