Does long distance ever work?

I don't get it.

I'm single, have been for about 4 years. Not bothered about being single - other that work colleagues keeping on asking about my personal life and why I'm not dating etc. I like doing and buying what I want right now. I'm 28, and my friends have all got girlfriends/married now, so perhaps I should be more open to the idea, but I'm not fussed right now.

My friend joined a dating site and met a girl, and they're now 'together'. They live about 3 hours away from each other so only see each other a couple of times a month, if that.

I just don't get how that can work out? Reason am asking is, I travel a fair bit, and if I were to meet a girl either abroad, or in a different city, are long distance relationships feasible?