I view it as an unfortunate affliction that people should try as much as possible to train themselves out of. The attachment to the word "like" is not the only kind of affliction out there, though.
Some people have that tendency to add an upswing to the end of every sentence, making everything that comes out of their mouths sound like a question-- "So I went to the store? And I saw this guy buying bread? And I recognized him from school? So I started talking to him?"
With other people, practically every other word is a profanity-- "So I went to the #$!% store to buy some #$%@ bread, and I saw this guy I knew, and I was like, 'Holy $#%@, that's Mike!'"
If what is coming out of your mouth is "So, like, I went to the store, like, and I was like, looking at bread, and like, I saw this like, guy I know, and he was like....." then you've got, like, a problem.
How to fix it? Can't really say-- probably the only thing to do is have people call you on it, and embarrass you out of it. People who curse too much have curse jars, but it's trickier with "like" since it's a perfectly useful word....in moderation. Maybe you could have your friends do something when you say "like" more than twice in one sentence? For example, they could make chicken noises....