I guess we all have our own ways at telling how well we are doing at exercise. It all depends what you're trying to achieve - weight loss, muscle growth, endurance etc etc. I find my clothes fit well or badly according to how well I'm doing so never bother with any real geeky stuff. I do know however, what my reps/weights/speeds are so I know roughly where I should be. My pool record is 126 length's (25m) in 55 minutes but am at present at 104 due to Christmas and being a bit lazy at present Plus I'm a bit older than you youngsters ;D