Many studies have been focused on the analysis of diferent factors that relate to the quality of life. And those studies have found a clear relationship between the quality of life, psychological well-being, and health. It is important to know those relationships and to know factors that can improve these three aspects simultaneously. And one of the most important factors is the realization of physical activity on a regular basis. This study analyzes the efect of physical activity on improving the quality of life (physical health and well-being) and its relationship with psychological well-being through two studies. One was a randomized clinical trial involving 98 low-risk incident cases of acute coronary syndrome, who were randomly assigned to an unsupervised walking program or a cycle ergometer exercise program. The other study is an expost-facto investigation with a total of 841 healthy subjects. We apply them questionnaires to measure subjective wellbeing, satisfaction with life, positive and negative afect, Short Form-36 Health Survey (SF-36), and the speciic Velasco-del Barrio questionnaire for post-myocardial infarction. This study concludes physical activity and exercise are key factors in an individual's perception for their quality of life, both in the area of physical and psychological health.