I have a super stressful job, so when I've had a bad day my instinct is to go for the chocolate. Going to the gym (yoga for me, but maybe a run for you!) is not only BETTER at managing my stress, but healthier too! My new mantra is Yoga is greater than Chocolate.
I go to the gym in the afternoons (can't do mornings) but can find a million excuses between my work and home. If I change at work instead of at the gym, having those gym clothes on makes my excuses disappear! And then I don't have to mess with the locker rooms, either.