I love hard rock when I'm lifting weights, but enjoy techno while doing any form of cardio. For weights I usually listen to stuff like Nickelback (not their ballads), Godsmack, Alice in Chains, Linkin Park, Limp Biskit, Green Day, Rise Against, Sick Puppies, Slip Knot...stuff like that. For cardio I love David Guetta, Tiesto, Fedde Le Grand, Deadmau5, etc...anything with a great beat and heavy drums...lol. I dont' have one genre of music that I listen to constantly. Most people cringe when they listen to my stuff because it's all over the place. On a playlist I could have Marlyn Manson followed by Justin Beiber!
You can't put an old head on young shoulders!