Another way to save time while exercising is to go to school and get groceries on a bike. Deepening on the distance it might take 30 minutes instead of 25, but it's a net win because now you got 30 minutes of exercise.
Trips to the grocery store are pretty much the only reason I use my car, I bike everywhere else. I hate grocery shopping, and so I go as little as possible. Biking home with $100 of groceries is tricky.
