It's very important to carry the right mentality in order to be successful.
What you see about yourself determines how you behave.
To be successful, you must see yourself as a success. To win, you must see yourself as a winner.
There's this interesting ancient story in the Bible where some Israelites, ten of them I think, saw themselves as grasshoppers in comparison to their opponents and so they couldn't garner the gots to confront them in battle. But just two of them saw themselves as well able to win the battle and take the territory. Your guess is as good as mine... They did.
It is your awareness that determines your behaviour.
It is your mentality that determines your performance.
If you think you can't, you won't but if you think you can, you will.