People exercise for a variety of reasons, everyone each having a different reason to exercise.  One person may exercise in order to enhance their physical performance (make a sports team) while someone else may exercise to enhance their daily cognitive performance.  Common known benefits of exercise include helping maintain a healthy cardiovascular system by preventing high blood pressure Exercising is different for everyone and varies greatly between age groups.  Regardless of the type of exercise or age group, exercising has profound effects on the body.  These effects can be exhibited mentally, emotionally and physiologically.  For example, a child's brain is not required to know how to pay bills or study for a college entrance exam.  A child has ample time and may even enjoy exercising.  As a person ages, their brain becomes more developed and is required to know how to perform difficult cognitive tasks.  The population becomes segmented into those who exercise frequently and those who do not.  College students and adults are busy with studying, work life has much less time.  The population becomes segmented between those who regularly exercise and those wo do not.  
    The segmentation of individuals who exercise and of those who don't may cause a gap to form in the cognitive abilities of the individuals.  
    When a person exercises the body turns to glucose and adenosine triphosphate (ATP)  for energy.  This energy helps an individual perform quick movements and changes in position as well as aid in muscle contractions needed during exercise \cite{klein}.  During exercise, heart rate is increased to allow more oxygen to be pumped throughout the body.  Blood containing nutrients and oxygen is delivered to active muscles.  This increase in oxygen can produce new brain cells and allows brain cells to function at higher levels \cite{klein}.  After exercising for a month, a person will start to feel less tired when they exercise as changes in the heart muscle occurred to adapt to the increased load of exercising \cite{on}.  Exercise also triggers neurotransmitters to be released from the brain.  Among these neurotransmitters are endorphins and gamma-aminobutyric acid (GABA).  Endorphins help reduce pain signals and GABA helps to improve mood and decrease anxiety when released \cite{endorphins}.  When a person exercises for prolonged periods of time the body is able to adapt to better suit the individual for physical activity.  Changes in the size of muscle fibers increase muscle size and in turn allow individuals to produce more force and power when exercising (lifting, running, etc.) \cite{on}.