There is an insight I've picked up from a couple of sources now, enough that it warrants mentioning.  There are a couple of creators that have learned to do pretty amazing things because they had a vision of something they wanted to do.  In order to do this thing they wanted to do, they had to go down a path of learning a bunch of things that you wouldn't necessarily have thought was directly related to their source 'path' so to speak.

One was a method of creating your own music cd's, the other was creating art that dealt with reflection.  On one hand, you had someone that wanted the ability to manufacture their own music and didn't see a path to doing so available.  On the other, an artist with a vision and a passion for mirrors.

I'm just going to share some links now, but I strongly recommend watching through these:

Derek Sivers : CD Baby
Playlist : Source
TL;DR : Learned web development, among other things, in order to bring his vision to life.

Daniel Rozin : Many many art installations
Wired Video: Source
TL;DR : Learned to program arduino in order to make thousands of 'pixels' of mechanical pieces shift and move in response to visual or other sensory input.

It's kind of another feather in the cap of how just having a destination or goal in mind can propel you down a path you may not have expected in order to achieve it, but also how that passion you build towards achieving that goal acts as the fuel you burn in order to get there.

In any case, I found both of these enlightening.