What Scares Me

I am a college student right now studying music. I love music and usually work pretty hard at it, but occasionally I will have days that I do not practice, and normally I feel like I have not practiced enough. Sometimes I wonder if I am sacrificing my future by being unwilling to work as hard for my dream. If I worked my butt off, maybe I could be a fantastic pianist, but at the current rate of practicing, I may have already turned fantastic into mediocre. That is what scare me. Could I be sacrificing what I could potentially be because I am or was lazy? Could I be wasting my happiness by not reaching my fullest potential as a pianist?
Forget about music. Think about someone you have heard about who has done so much with their lives. I heard of one man who translated one book into forty different languages, and of course, accomplished much more. Then I look at my life, and wonder, "have I wasted it, have I used it to its fullest potential?"
Forget about my small life. Imagine if all of us used our lives to the fullest? Would cancer be cured then, would hunger dissipate? Would wars stop because we took extra time to figure out a compromise and saw life and energy as a greater good than money? What are we wasting by our complacency, our laziness? What have we missed?