This is actually...a really interesting thread!
Well, I don't smoke, I don't and never will do drugs, I drink very rarely, I'm single...but yeah, I'm happy. My circumstances are going to be different to everyone else's here, but the long and short of it is that, right at this very moment...life is starting to make sense.
It's difficult to explain. I look forward to having lots of sex, but at the moment, am content without it. Someone I had a major connection with has come back into my life, so the future's looking bright. I've been completely miserable at university, so have taken the decision to just quit and get a job (please, nobody bash on about the job market, I already have a job sorted) and deal with the consequences. To me...knowing I'm growing up and making decisions that I personally have to live by for the rest of my life...it makes me happy. Regardless of what happens next, I think I'll be alright. Above all else, changing my life has made me the happiest I've been all year.
So yeah, I appreciate that you're having a great time doing drugs, shagging everything with a pulse, drinking yourself into oblivion...enjoy it. It won't last long, because when real responsibilities hit you, you simply won't have the time for it.
My life isn't boring without those things, I work 9-5 at a dog creche (sounds poncy? Think again; it's amazingly rewarding) so my time is taken up with that, but other things give me pleasure: reading, gaming, making music, conversation...
I see from your profile that you're a student. Good luck with your studies. But you're a normal student if you do all of those things, simple as. But later on, when schooling is in the distant past, you'll have other things to fill your time. It's the way life is. It doesn't mean it'll be boring or any less fulfilling, but different things will satisfy you.
Sorry, this is a long post! I haven't posted on The Escapist in a while, so I needed to make up for it =D
EDIT: Sure, drinking is hellishly fun, I'm not denying that. I bet getting high is fun too, not that I'm gonna try it. For different people, life is about different things. Someone's life isn't necessarily boring because they abstain from all the things you mentioned. Maybe...they're just in a different place to you, where other things bring them joy *shrugs*