I am 13 and love computers, everything about them. Inside and out. I have taken apart and put back together my old family PC. I am so interested in computers, I would like to make this my future. Is that a good choice? How can I prepare myself now?
Do you enjoy solving problems and are you able to spend all day (and sometimes all night) staring at code? If yes, then you might like a career in programming. If you want to get the jump on others, start writing code now.
Disclaimer: There is a never ending debate on which programming language is the "best" to start with. I'm not suggesting that Python is that language. I only suggested it because it is an open platform language (you can program on Windows, Mac and Linux) and the HTML version of that book is free (I picked up the PDF version for $3). I also think that book is great for beginners because it is written in a way that explains things well for a beginner. It drives home the importance of paying attention to details and understanding the fundamentals first.
If you really enjoy computers then I think it programming is something that you should at least know a bit about even if you don't use it professionally. It helps give you a deeper understanding of how a computer works. And when something doesn't quite work the way you want, you can create your own tools.
I don't program professionally, but I do enjoy it and use it quite a bit on a personal level. I started out with Visual Basic 6 some time ago and then moved into .NET. I've done some Python and am starting to dig into C. Like randomizer suggested, there is no reason that you cannot start now.