One more idea: why drive to the gym... or on a lot of other short trips. I know we don't always have the time to walk or take a bike, but a lot of times it takes almost as long to drive as it does to bike.
Last year we had our old beater bikes fitted out with solid foam innertubes. It wasn't all that cheap, but we have no flat tires now. Just get on the bike and go. Yes, they are a little harder on your behind. But for the short trips that we make, it is just so great.
Just a thought.