training will injured or sick is usually not a great idea for me...I was DEAD tired and was grinding thru and hrt my shoulder - only time I have ever been hurt in the gtm
my buddy's a nationally ranked powerlifter (ie, squats well over 800lbs in competition) and he takes a week off after every competition.
My wife is the only thing in my life that I would miss the gym for, but she goes out of her way to accomodate it that it almost never comes up
if during my warmups, a certain muscle I'm working feels odd, then I go home. I've learnt from the past not too push things.
I always like to do better than the last time I was at the gym. If I lift less reps, then I get more depressed than if I didn't workout at all
Its better to skip, than to try and fail, when it comes to workouts. This way I keep my motivation and morale up. Nothing worse than forcing a workout to then lift less, and then you've added even more fatigue, and extended your recovery further.
Well this is the case for me anyway - motivation is not a problem for me, but backing off is!