Exercise can help a lot with stress relief, the endorphins do it. The key is to find a form of exercise you enjoy, so it doesn't seem like another obligation. And go slow at first, give yourself time to adjust.
My mom has HBP and one of her doctors recommended swimming. She loved it but hasn't gotten back into a routine yet since her last hip replacement. But she goes out walking when weather permits. Walking can be an excellent form of exercise.
Me, I started rollerblading when I was 47. Even on the days when I feel flabby and out of shape, it's so much fun I don't think of it as exercise... but it sure is! I wish I could do it more often, especially in the winter when it's just too cold and the roads are sloppy with snow or slush. The nicest thing about going out for my "flying ride on little wheels" - I like being outside, skating along the Hudson River with my iPod - it drives all worries from my mind! I get into a zone and everything seems to fade away except the roll, no matter what problems I might have going on.
A meditation practice can also help clear the mind wonderfully. Worrying is just borrowing trouble from the future... I know, I do a lot of it myself.
Congratulations on choosing to take care of yourself. Good luck finding your physical bliss!