Something to note: you rarely feel worse than you did before after you exercise. On gross, grisly days during the winter, when absolutely nothing goes right it is important to try to squeeze in at least a twenty minute break outside. I'm not talking about the sweaty, germ-infested gym. I am talking about outside in the fresh air where your body can absorb some sunlight and your lungs can fill up with air that hasn't already cycled through someone else.
If you have small children you can accomplish this by sticking them in the stroller and heading outside. Even though they are just along for the ride the fresh air does them good. They'll sleep better ...