I actually dread the day when I reach my full potential.
That probably sounds really stupid, but here's my reason:
You can't dream bigger than what you know your potential to be, but you never know your full potential until you reach it.
Thus, I hope I never reach my full potential. I want to always have it just out of reach, because then I can still do amazing things while dreaming as big as I want. I'll never know if my full potential really is just out of reach or if it's actually miles above me, and therefore I can keep dreaming of things that are miles above me. I also believe that dreams cause you to grow as a person, so by enabling myself to have these big dreams I gain more and more potential.