I just do what I do when I'm with someone, only more often
I've never really worried about being alone, as long as you've got good friends and keep active it shouldn't be a problem.
Being with someone can be great though, don't get me wrong but if you have a great life anyway it's just a bonus having someone to share it with rather an inate neccesity.

I do know a lot of people that don't feel complete unless they're in a relationship though, and they always seem to be the ones that make the worst mistakes with relationships. They seem to be of the opinion it's better to with anyone, even if they're not great people than be alone. Whereas I won't let anyone into my life unless they're absolutely awesome and my life would be that little bit worse without them around.