Working out means sweating and sweating means dirty clothes. What are the chances you are going to want to workout Monday morning if all your workout wear is still stinky from the week before? I'd say the chances are low.
Take time tonight to wash those sweaty sweats so they will be ready for your workout tomorrow and for the rest of the week. If you exercise in the morning, go ahead and lay out your outfit the night before — heart rate monitor, iPod and all. You can roll out of bed, get dressed, have a bite to eat, and get to the business of exercising early morning style. If a morning workout is not your scene, pack your gym bag tonight, put it by the door and eliminate the excuse that you forgot your bag.