Exercise: Regular exercise produces more beta-endorphin, a hormone that controls stress and improves mood. Go for a run, play some tennis, ride your bike, or punch a punching bag.

Get enough sleep: Though it can be hard to find enough time, getting adequate rest is very important. Being tired can lead to more sadness and irritability.

Create: Get involved in some sort of project, like starting a journal or diary, building something out of wood, or starting an art or music piece. Writing can help you organize and express your thoughts and feelings and will make things more manageable. Don't worry about grammar, spelling, or punctuation; the important thing is just to get your thoughts on paper. Do the same thing with paint, sculpture, music, or other art forms. Put your feelings into your artwork.

Cry: There's nothing wrong with crying; in fact, it often makes a person feel better. However, if you find that you are sad, irritable, bored, or hopeless much of the time, or if you just can't seem to shake the blues, you might be depressed and need help from a counselor or doctor. If you're feeling stressed or angry a lot of the time, getting help could be very useful for you.

Wait: Just as you can get into a bad mood for what seems like no reason at times, that mood can also pass. If your negative mood sticks around too long, though — or if it's interfering with the way you deal with friends, parents, school, or activities — then you may want to talk to a school counselor, parent, or therapist about what you can do to feel better.