Programming is just a part of I.T. To me it's more like, "Why did you decide to get a Computer Science degree instead of an Information Systems degree?" There's more creativity to build stuff in programming than say, network administration. The network admins do build servers, VMs, the actual network, and things like that, but a lot of their time seems to be administration of the system. Whichever one you decide, you should know at least some about the other one. Both require critical thinking skills for troubleshooting, but in different ways.
For me it was decided when I was about 13 and banging out BASIC apps from books. Ever since then I had a fascination with computer programming and it stuck with me. I just don't have that same fascination with other I.T. jobs.