Ok I now want a body like Brad Pitt.Is it wrong to want to change everything about yourself to impress girls?

I don't quite know how to write this and I don't know if it will make any sense, but here it goes...Ok so today I was down town with two of my pals and the sun was splitting the stones. Which in my country is very rare! Anyway..as we made our way down town I began to notice that nearly every single guy my age who was wearing a t-shirt was build as hell. I mean these guys had mive arms, shoulders, and were all in really good shape. Everywhere I looked lads were walking around with these great bodies, and for the first time in my life I felt really self-conscious about my own. I'm a lads lad through and through and am the least vain person in the world, but as I watched these guys walk the streets with their hot girlfriends, I thought to myself "I want a body like that" and then thought "I want a body like Brad Pitt". I had to slap myself and realize that I just feel out of place because I am different. But instead of embracing my difference I wanted to conform myself to the way everybody else was. The way the guys in the Armani ad campaigns are with their perfect bodies and washboard abs. Is this normal? I mean should I embrace my different type of body?my scranny bod, and if so why? I haven't put the hours in the gym, I haven't worked out. Whats to be proud of? I mean I wouldn't go around showing all my fiends and family an F I got in an exam so why would I be proud of this? Especially when it is actually something I can change. I don't know guys, is this normal?and if so what should I do. PHEW! That was a rant and a half!(he says while wiping the sweat of his forehead!)