I feel like this sometimes. I go to the gym thinking....I'm not really into this today, maybe I will just hit the back then get out of here. So I hit the back and hit it hard, and as I am hitting it i'm thinking maybe I will go ahead and work the abs, I will feel better if I hit the abs. Then as I am doing it, i'm thinking :45 min of cardio and I can enjoy the rest of the day, feel pretty good about myself. For me, getting my ass in there is the battle, once I am there it clicks for me... But every 2 months of training I take 5-7 days off for rest and I usually come back harder and stronger.