Be yourself. Changing for anyone is pointless and very short term. If you do what you like and someone likes you for it, you have the basis for a long term relationship.
Try to be more social, Go outside, get rid of the monitor tan, bike or play soccer or something that you like to do that results in you meeting people of the opposite gender. Then you already have something in common to talk about. but the most important rule is BE YOURSELF!.
Gotta love these self-contradictory motivational speeches, you just said changing for anyone is pointless and then tell them to immediately do change themselves by being more social etc. some people just don't do well in the usual social settings, I know I don't

READ, before attacking the comment!!

Not self contradictory. I said "Change for yourself", never change for a girl or for anyone else). Obviously, your current habits/hobbies don't put you in a place conducive to meeting girls you like/want/care to be with. So change THAT.
There may be a problem with your lifestyle in that you may not place yourself in enough situations to be able to find "the one" to be with. What would you offer a girl? Think about that. Are you interesting? Are you boring? Are you funny or really smart? Everyone has some quality that makes them interesting to someone else. Find yours and capitalize on it.