It's sort of like deciding to be a music major when you've never played an instrument before. How do you know if you even enjoy it before starting down the long path to getting a degree in it?
That's highly debatable. A lot of people including my old compsci professor seem to believe it's largely something someone either can learn to understand or can't. I've noticed myself that students seemed to either "get" programming or not, both in a class I took in high school and the compsci class at my first college. This article on the issue is worth reading: http://blog.codinghorror.com/separating-programming-sheep-fr...
http://retractionwatch.com/2014/07/18/the-camel-doesnt-have-...
Yeah, but most people don't know that. Sure, us nerds figured it out, but most people are shocked that I learned to code at 13. I thought it wasn't that difficult. I don't think I'm smarter than most, I just wasn't scared off by the technical details.
These days you can be be learning to code using any number of slick web sites in about 5 minutes.
I was too focused on my high school academics (and goofing off) to devote enough time to properly learn to program. Once software became a part of my academics, I found that I got much more better explanations of how things fundamentally work. I also finally had more time to practice.