It has social and personal purposes. If you look great you feel great, like I said I used to suffer bouts of depression maybe once or twice a week sometimes bad enough for me not to go to school. About a month into working out after the initial stage where you have to force yourself to go, that depression completely vanished. It's a good feeling when you wake up every morning refreshed and ready for anything. And socially it's a boon, I get guys wanting to hang out with me/go out to bars with me because I look good (shallow I know but that's the world we live in) and girls hooking up with me for no reason other than my body. You talk about the modern age, all people in the modern age care about is appearance.