Make it a closed predictable activity: perceived control. Exercise 20 to 30 minutes in duration, moderate intensity, 2 or 3 times per week. Tend to record/remember negative experiences moreso than the positive experiences. Group level vs. individual level: choose to hang out with friends rather than exercise. Brain gets blood, oxygen, endorphins released =happy: changes in brain neurotransmitters (e. g. , norepinephrine, endorphins, serotonin) Increase in maximum oxygen consumption and delivery of oxygen to cerebral tissue: reductions in muscle tension, structural changes in the brain (seen through mris) Psychological explanations: enhanced feeling of control, feeling of competency and self-efficacy, positive social interactions. Improved self-concept and self-esteem: opportunities for fun and enjoyment exercise and changes in personality and cognitive functioning. Exercise programs conducted over long periods are associated with moderate gains in cognitive functioning. Acute exercise increased cognitive functioning in the form of working memory only for people low in working memory: short-term memory can benefit from acute exercise.