Everything has boundaries. The same holds true with thought. You shouldn't fear boundaries, but you should not be afraid of destroying them. That's what is most important if you want to be free: respect for and exasperation with boundaries.
Believe in your infinite potential. Your only limitations are those you set upon yourself. Believe in yourself, your abilities and your own potential. Never let self-doubt hold you captive. You are worthy of all that you dream of and hope for.