I got into shape because I took kick-boxing lessons every day to prepare for a fight scene with Taylor Lautner. I really wanted to lie down and eat Chinese food, but I kick-boxed every morning and ran. If someone was filming you with your kit off, you'd do the same thing.
I like both music and acting, and they both have a lot in common - timing, immediacy, stuff like that. But acting is more regimented. You wait around for hours, you don't get to write the script, you get hired. Music represents me better. I'm not acting; I'm just expressing myself.