If you want total confidence, you'll have to live it.
I call this the power of Think-Say-Do. Think of a triangle, where your thoughts are confirmed first orally, then physically by your actions. Collectively, the three paint you into a positive corner, reinforcing your inner belief in yourself and your team(s). By uniting thoughts with words with deeds, you powerfully reinforce your confident point of view.
Thoughts are not enough. They are private and easily revocable. They might expand (ala The Secret), but unless they manifest in the real world, they don't leave your random-access-memory and penetrate your mind's core. Words are not enough. Talking about your confidence spreads the idea around and likely generates a response in others — but words are just words. It's easy to say you have financial confidence, but to double down for your favorite charity is the real deal.
Action is not enough. You won't bolster your confidence by being mindlessly grateful in private. You need to think about it, just like when you work out at the gym. By connecting your mind to your action, you focus your energy. By talking about your actions, you commit yourself to them and likely influence others.