I've gone into every job interview I've had with the attitude that I'm a hot shot who is gracing my employer with my willingness to work for them[1]. I've gotten offers at about 50% of them, which means that I've turned down more companies than have turned down me.

Confidence really does work. If you sincerely believe in your abilities, it's much easier to convince others to believe in them.

[1] This is not mutually exclusive with respect or humility. It's quite possible to believe you have a lot to offer your employer while also believing they have a lot to offer you, and then the job interview process is just a matter of negotiating the right fit.