The best alternatives to economically productive work are equally productive in different domains. For example, take gardening. You might be surprised at the quality of aerobic exercise you get working a large yard and garden. I recently took a heart rate monitor and found I could replace my morning jog. My heart rate was actually higher on average, and the sense of purpose was a welcome distraction from the work.
Unfortunately few are taught these kinds of healthful alternatives. I can only imagine what a difference in health and cognition there would be if schools taught hands-on agriculture and gave students garden plots.