The objective of this research was to analyse the differences in physical activity, basic psychological needs, motivation and responsibility in students. A sample of 109 participants was chosen (M = 16.29, SD = .95), who were given a questionnaire to assess their satisfaction of basic psychological needs (PNSE), motivation (BREQ-2) and responsibility (PSRQ), together with a physical activity measurement instrument. The participants were grouped for analysis according to the percentile of physical activity in "low active", "some active" or "very active". The results indicated no differences according to gender in physical activity. On the one hand the very active group had higher values of physical activity with respect to the rest of the groups, and these values were higher at weekends compared to the rest of the week, whereas, low and some active groups obtained higher values during the week. In addition, the very active group presented higher values in intrinsic motivation, autonomy, competence and lower in amotivation. We concluded the need to promote physical activity especially at weekends, encouraging the satisfaction of basic psychological needs to obtain higher levels of motivation.