I have an eclectic taste in music. I like jazz, rock, pop, dance, standards, 80's pop and the current computer created pop songs. I just want to lift to something with high energy. No ballads.
If you own a gym, you have to please the majority of the people. If you only like rock consider women like music you can dance to and that isn't rock. Few black guys listen to rock. Urban guys don't listen to 70's rock.
Get an Apple Ipod. It's tiny and will hold over 50 albums. The sound is incredible. The battery last for ever. It clips on your shirt. I just got one and I'm not a tech guy and it's idiot proof to use.
One thing is sad. There doens't seem to be any current rock bands making new music anymore. The Foo Fighters and Nickle Back are the ones that come to mind. Rock does seem to be dying.