It's what you choose to believe that makes you the person you are.
According to dictionary belief means an acceptance that something exists or is true especially one without proof. It is something that is the need of humanity. But we cannot believe everyone because its 21st Century and everyone cannot be trusted but who we believe or what we believe is critical to our success in every area of our lives.
Many times, in our lives, when faced with challenges we look at the circumstances and, based on what we see, we give up on our dreams and goals. Doing this is a guarantee of failure. Believing that it is possible, on the other hand opens our mind to coming up with solutions and actions that will enable us to achieve what we want.
Belief is a habit and it must nurture and strengthened by constant exercise. Belief can also be called faith and the Bible has some interesting things to say about faith. Jesus said that if you have faith like a mustard seed, you can have mountains. Too many of us see the words mustard seed and miss the real point. You either have faith or you don't! there are no degrees of faith. It's like being pregnant. You either are or aren't. You can't be slightly pregnant.
So, we either believe it's possible and act accordingly or we don't. The exciting thing is that it's a choice and only we can make it. Believing and acting accordingly will activate the Law of attraction and we'll begin to draw into our lives what we need to succeed.
You need to believe in things that aren't true. How else can they become?