In a study published in the journal Psychosomatic Medicine in 2007, researchers found that just 30 minutes of light- to moderate-intensity exercise (think: brisk walking or jogging) was enough to alleviate many symptoms of major depression and may be just as effective as medication.
The exact reasons are unknown, but the researchers speculated that a number of factors are at play: from being distracted from negative thoughts to balancing key neurotransmitters, including serotonin.
Exercise may also help people with anxiety disorders. When exercising, the body produces many of the same physical reactions as it does during a panic attack.
According to a study published in the journal Depression & Anxiety in 2008, exercise may help those with anxiety disorders by normalizing those sensations and teaching the brain to associate those reactions (heavy perspiration, increased breathing, elevated heart rate, etc.) with safety instead of danger.