Getting bored quickly?

I get bored with things quickly and move onto new things. Like with guitar, I played for about a year and, even though I was off to a good start, I got bored and stopped. Another example is TF2. It's a fun game and I was alright at it, but I got bored and stopped playing it. I could be because I never have anyone to game with but I've been playing alone most of my life. I become average at everything and then move onto something because I get bored. I can never become better than average or even wrap my head around how some people become as good as they are. Even if I'm good, in my opinion, at some things, I get bored with it.