If your are feeling angry, hitting a punching bag after a bad day can actually make you feel worse. You want to diffuse your feelings, not intensify them. Do a vigorous aerobic workout instead.
If you feel sad, even a mild exercise can lift your spirits, and the benefits will last for two to four hours afterward.
If you are feeling stressed, swimming or running, or doing something that has a meditative component, like yoga, will help to calm you down.
Not in the mood, suck it up and get your butt to the gym.
