When I have trouble getting up in the morning to exercise, I will sleep in my gym clothes the night before. One less step between waking up and working out!
I do this more in the winter, when it's haaard to leave the warm bed. I leave my socks and shoes by the door (no, I don't sleep in my sneakers..) and make sure I have everything else I need prepared the night before. Sometimes it feels like I wake up on the treadmill!