Perfect solution, and I am not being a smart-ass:

Go hit the gym, ride a bike, or run for at least 45 minutes real hard.

Come home, have a big, *healthy* dinner within 30 minutes of exercise- this is actually the best way to promote personal health, too!

jerk off/get laid/get a blowjob (getting blowjobs work the best IMO)

Pass the hell out.

Worst case scenario, have 2-3 drinks, TOPS, if you still can't relax.

But, if you can't relax from getting a blow job, you may be beyond help.

lol.