Recent evidence suggests nonspecific goals may be beneficial for physical activity adoption, however, it is currently unclear which variation of nonspecific goal is most beneficial. Therefore, this study compared open, do-your-best, as-well-as-possible, SMART goals and no instruction (control) on distance walked during a series of six-minute walk tests, as well as ratings of perceived exertion (RPE), mental effort, autonomy, and interest in further exercise. In total, 82 healthy adults ranging from high to low levels of physical activity (59 women; 23 men; M age = 48.10) took part. Participants were randomly assigned to either: open goals; do-your-best goals; as-well-as-possible goals; SMART goals; or control. Participants in the goal groups completed a baseline and then two manipulated attempts of the six-minute walk test, while the control group followed the baseline instructions for all three attempts. There was no significant difference in the distance walked by participants pursuing open, do-your-best, as-well-as-possible and SMART goals; all of whom walked significantly further than participants in the control. Open, do-your-best and SMART goals resulted in significantly higher RPE than control. Do-your-best goals resulted in significantly greater mental effort compared to control. Open goals resulted in significantly higher interest in repeating the session, and significantly higher interest in pursuing a program, compared to control. This study provides further evidence of the potential benefits of nonspecific goals for physical activity. Findings suggest each version of nonspecific goals leads to different psychological outcomes, and that open goals may be the most beneficial form of nonspecific goals for physical activity. Lay summary: This study compared three forms of nonspecific goals (open, do-your-best, and as-well-as-possible) against SMART goals and a control in a series of six-minute walk tests. The findings illustrate the potential benefits of non-specific goals for physical activity, of which open goals appeared to be the most beneficial.