In order to prevent chronic diseases, individuals should actively pay more attention to their own health conditions and not merely rely on the medical system passively. The purpose of this study attempts to investigate the impact of individual health behaviors, specifically the exercise behavior, to his/her health-related quality of life from “positive” viewpoints by applying Deci and Ryan’s self-determination theory (SDT). Four hundred and fifty-nine undergraduate students at National Taiwan University participated in this study. Four sets of questionnaires concerning the basic psychological needs in exercise, health motivation, exercise behavior, and quality of life were used in this study. The quantitative analysis of the questionnaires was conducted through descriptive statistics and structural equation modeling (SEM) in order to indicate any relationships between two latent factors or a latent factor and a manifested variable. Results of this study showed that there are stronger relationships between the basic psychological needs in exercise, the intrinsic health motivation, the exercise behavior, and the psychological domain of quality of life. Furthermore, the basic psychological needs in exercise are also linked directly to the psychological domain of quality of life. The results also indicate that the viewpoint of SDT can be used for predicting the health-related quality of the life. There is the relationship between the basic psychological needs in exercise and health-related quality of life. The study concludes that the satisfaction of three basic psychological needs can increase personal intrinsic health motivation, enable people to care about their own health more voluntarily, increase the possibility to do health behavior, and have better health-related quality of life.