It is an enlightening exercise when consider the ratio of return on all activities where you contribute your resources.
With savings, you can put it in the piggy bank and have a one-to-one ratio ($1 in will equal $1 out), or in a savings account which will provide you a bit higher return -- or you can invest it in stocks which should earn you a much higher ratio in the long run. With investing, the activities of others are rewarding you.
With your job, you can get paid for each hour or salaried equivalent -- or you can become an entrepreneur or business owner and earn income from sales and the work of your employees, thus benefitting from work you are not directly doing. Your one hour of work as an owner could equate to much more than one hour of return in ultimate pay.
With fitness work outs, you can go for walks or do aerobics to gain direct benefit, but with strength training the ratio is higher. Resistance training boosts your metabolism and can actually help burn calories after your workout. Again, you are benefitting beyond direct one-to-one input: 30 minutes of aerobics burns calories for 30 minutes, but 30 minutes burns calories for more than 30 minutes.
I don't know anyone who feels like they have too much time on their hands. To make the most of what you do have, consider what activities you invest in. Do you put your effort where there is a one-to-one ratio and you earn all the benefits yourself, or can you leverage synergy by participating in practices where others are working for your gain?
-- beth triplett