Marilyn,
I will have to second what Princess said here:
If you don't find something you enjoy, chances are you won't stick with it. You may never get a rush or endorphins, but you will enjoy the company and the positive effects on your body.
Mozz and I don't always WANT to crawl out of bed to walk, but we always have such a fun time talking. We're both groggy and sleepy and it's prime time to tease each other about bedhead and tukus breath. It's really a nice way to wake up...private time conversing with your best friend!
Andi