So basically you want to be a world class guitarist, but you are afraid that your goal may change. You shouldn't be afraid of that: if, some day, you decide you don't want to be a guitarist anymore, just forget about it.

Anyway, you can definetely achieve your goal: if you can imagine it, you can get it, simple as that.

As for the "how", look for creative visualization Very briefly (google it for more details): if you visualize yourself as already being a world class guitarist, you'll create this mental image in your mind and your brain will perceive it as real because it cannot distinguish what is imagined from what is real (otherwise we'd be always lucid in our dreams, for example). This imagine will then be transferred to your reticular activating system which will then find ways to achieve that image in the real world in a totally unconscious way. You may for example bump "accidentally" into a person who can help you in your journey while doing that

This stuff is powerful, so I really suggest trying it, I've achieved great thing with it. Bear in mind though that if you stop thinking about, this thoughts will go dormant and your reticular activating system will focus on something else, so don't worry about possible changes of mind.

Have fun with it ^^