'Self-Belief' is a quality shared by winners across all fields, from sports, to business, to trading. There is a wonderful poem, written about 100 years ago, which nicely captures and summaries this point. - I advise many of my trading clients to print this poem off and keep it close to hand:
If you think you dare not, you don't,
If you like to win, but you think you can't
It is almost certain you won't.
If you think you'll lose, you're lost
For out of the world we find,
Success begins with a fellow's will
It's all in the state of mind.
If you think you are outclassed, you are
You've got to think high to rise,
You've got to be sure of yourself before
You can ever win a prize.
Life's battles don't always go
To the stronger or faster man,
But soon or late the man who wins
Is the man WHO THINKS HE CAN!