You are currently paying $15 per month for gym membership. You are trying to decide whether it's worth it to cancel the membership and instead to buy a set of fancypants all-in-one exercise equipment for $678. You expect the set to have a useful life of 20 years. If the real rate of return on investments is anticipated to be 6.9% APR, what is the net benefit to you of buying the equipment?

Assume your membership is paid for the current month, so you'd be starting your membership savings at the end of the month.

Assume also that you won't get bored with your exercise equipment and derive no utility from exercising with others. :)