So, on top of paying for a gym membership and not using it, you're paying an additional $10 for each time you should go but don't, and it's... still a good deal?
But of course! Since when are human beings perfectly self-consistent? The part of me who wants to sign up for a gym membership is concerned with long-term planning, and thinks it would be a good idea to remain healthy into older age; the part of me who actually has to go to the gym, here and now, feels far more concerned about the fact that working out sucks, and would very much rather do just about anything else.
Just to be clear, it's not necessarily $10 each time you don't go. You set yourself a target like "4 times this week" or "10 times this month" and it's when you fail to hit your own target that you lose the money.