<human>:  What is the most effective way to exercise that doesn't take too much time?
<bot>: The most effective way to exercise that doesn't take too much time is to do high intensity interval training (HIIT). HIIT involves short bursts of intense activity followed by periods of rest. This type of workout can be done in only a few minutes and has been proven to be one of the most effective forms of exercise for improving aerobic capacity and burning calories.