I don't know about physical health, but sex certainly keeps me sane. If I go too long without, I start to get all edgy.
I sometimes think many of the world's violence problems could be solved if the extremists (on EVERY side) were to just get laid more often. Ever see the movie Dangerous Beauty?
That's my "solution" to nation building and stamping out radicalism: saturate the area with internet-enabled laptops and providers. Boom, problem solved.