That voice in your head that says “No”, “I can’t”, “It won’t happen” – yeah, that one. It’s gotta go if you are to push beyond what you think your limits are. Replace that voice with one that believes you can, and then make it happen.
Believe you can – or you won’t.
One of my favorite books as a small child was “The little train that could.” Deeply embedded this concept from an early age. Still refining it daily.