Psychological aspects of physical exercise

Addiction to exercise
Physical exercise releases opioid peptides or endorphins, opiates that exhibit synergetic effects with other neurotransmitters, causing exercise euphoria, also known as "runners high", and causing addiction to physical exercise and possibly decreased sex drive. This usually leads to over-exercising; a person suffering exercise addiction is often described as a "gym rat", "body nazi", "exercise freak", etc.

Stopping excessive exercise suddenly can also create a change in mood. Feelings of depression and agitation can occur when withdrawal from the natural endorphins produced by exercise occurs.

Does exercise helps brain function
In the long term, exercise helps the brain by:
 * increasing the blood and oxygen flow to the brain
 * increasing growth factors that help create new nerve cells
 * increasing chemicals in the brain that help cognition

Papers

 * Google Scholar