Is it normal to want to do whatever it takes to fulfill my dream?

I have wanted to play the guitar and become a muscician for quite a while now because thats what i want to be when i grow up. im planning on buying myself a guitar, but im not sure if i should or not because i dont know if my singing is that good or if i'll even get any where with this dream of mine. i just dont want to be like one of those people who say things like, "i always wanted to do that" or in my case, "play that instrument"...I actully want to DO this instead of this just being my continuous dream.