"Believe you can and you're halfway there." Theodore Roosevelt
I feel this quote means if youu want to do something but you dont feel you can do it then you will never achieve it, so if you belive you can do it then you will achieve it. I can relate to this because when I wanted to start soccer I did not think I could do it but when I belived I did it and now I an a competitive soccer player.
So all you have to do is belive and you will beable to do it.