When people say they are learning to play a musical instrument what they should say is: "I'm going to take a test, if I am musically inclined then I will pass, and if I'm not, well, then, I may take up Sodoku."
Let's face it - when you hear of someone learning to play - one of two things are said, "Oh - he's a natural - just picked it right up!" or "Well, he's trying. It's just taking some time," followed by "He gave up and went on to another hobby - scrapbooking."
So that's my observation - when it comes to mastering the piano, the guitar or even the freakin' oboe - you've either got "it" or - like me - you don't.