Mood Food

Mental Attitude: Exercise Your Mood.
Regular exercise reduces symptoms of moderate depression and enhances psychological fitness. During exercise, plasma levels of endorphins increases in the body, which can have an effect on the psychological state. Endorphins are hormones in the brain associated with a happy, positive feeling. A low level of endorphins is associated with depression. A recent National Health and Nutrition survey found physically active people were half as likely to be depressed. Exercise also boosts the neurotransmitter serotonin in the brain. Neurotransmitters are chemicals that send specific messages from one brain cell to another. Though only a small percentage of all serotonin is located in the brain, this neurotransmitter is thought to play a key role in keeping your mood calm.
WebMD.com