See food diet, Babe.
Actually, read up on body somatypes. If you have itty bitty wrists and slight frame, likely, you're never gonna' be real hunky (ectomorph). If you have big wrists, and larger bones (endomorph), you'll gain weight more easily, but, tend to be a bit "smooth" (in terms of muscle definition). If you have a naturally narrow waste, average to larger bones (wrists, generally), and wide shoulders, you'll probably pack on muscle easily and not have a bunch of trouble staying lean (mesomorph). If you're a mesomorph, who does all this with incredible ease (mounds of lean muscle), you're what's called a super-meso.
You have to learn how to work with your somatype. I could go on for many paragraphs here, but, you need to do your own discovery.
I'm an extreme meso, bordering on super-meso. I weighed 175, 5'5", in high school and had 12% fat, and knew nothing of nutrition. I look at weights and get bigger. In my later 20's I was 230 at 10% to 12%, without really even knowing what I was doing. I've met guys, like my friend, Sage Watson, who is a complete super-meso http://profile.myspace.com/index.cfm?fuseaction=user.viewprofile&friendid=12643819. Sage will likely end up a pro bodybuilder, if he pauses from partying long enough. LOL.
These are the facts of body types. While anti-aging, nutrtion, AAS, smart training, and so on can help you realize your full potential, and help with recovery, they can't change your underlying genetics. I.e., a skinny guys on juice, is still a skinny guy underneath, or a guy who is a supermeso can be a giant on gear.
Some of us are more cut out for the Addonis thing, but, it is what it is. I'm never gonna' be in the NBA. Ain't gonna' happen.