If we did all the things that we are capable of doing, we would literally astound ourselves.- Thomas Edison.
There was an English teacher who said to her class: “With some effort and hard work, every person in this class will get an A or A* in the final exam.” Most students thought that the teacher was deluded. But the teacher ignored this lack of belief and kept repeating the above words. The students finally started to believe that as well. And, when the results of the exam came, all of them had achieved an A or A*. Theirs was the only class which managed this, despite the similar ability of students in other classes.
This is what a self-fulfilling prophecy is: it is, in the beginning, a false definition of the situation, but one which evokes new behaviour that makes the original false conception come true. This happens because your positive(or negative) belief about a situation makes you take on a different attitude and display different behaviour to someone who has not got the same belief.
That is what happened to the students who got A or A*.
If you can understand and internalize this, then you can understand the power of belief. You can understand how daring to dream will make you successful.
But you have to believe in yourselves. You have to believe that you can do things which your logical mind might view as impossible.
But belief is not the only thing. You also have to have some ability. You need not be gifted but you must have some ability. You also really would want to achieve the goal, rather than the trappings of the goal. You need to really want to be a singer and not want the trappings of a successful singer. You have to play to your strengths that you are more naturally suited to and enjoy.
And belief can propel you to achieving them with work and effort.