There is no destination. There is only the voyage. True confidence comes with experience. You are 26, so you have had a lot of experience, but we never stop learning. In the meantime be patient and never compare how you feel with how other appear. At your age, “successful people” are just the ones that hide their fears of inadequacy better. Work hard gather every opportunity for experience you can, accept that failure is just a way to eliminate ways to do things in future and be sure to find time to enjoy the voyage. And read the Confidence Gap by Russ Harris.