Here are 12 quotes that prove it:
1.)“In order to succeed, we must first believe that we can.” ~Nikos Kazantzakis
2.)“Believe you can and you’re halfway there.” ~Theodore Roosevelt
3.)“Our belief system is just like a mirror that only shows us what we believe.” ~Don Miguel Ruiz
4.)“Whatever the mind can conceive and believe, it can achieve.” ~Napoleon Hill
5.)“Don’t limit yourself. Many people limit themselves to what they think they can do. You can go as far as your mind lets you. What you believe, remember, you can achieve.” ~Mary Kay Ash
6.)“If you can imagine it, you can achieve it. If you can dream it, you can become it.” ~William Arthur Ward
7.)“Nothing stops the man who desires to achieve. Every obstacle is simply a course to develop his achievement muscle. It’s a strengthening of his powers of accomplishment.” ~Thomas Carlyle
8.)“Think of yourself as on the threshold of unparalleled success. A whole, clear, glorious life lies before you. Achieve! Achieve!” ~Andrew Carnegie
9.)“If my mind can conceive it, and my heart can believe it, I know I can achieve it.” ~Jesse Jackson
10.)“We are shaped by our thoughts; we become what we think.” ~Buddha
11.)"What matters is not the idea a man holds, but the depth at which he holds it." ~Ezra Pound
12.)"Anything is possible once you believe you are worthy of achieving it." ~Jason Pockrandt