The most effective way to overcome self doubt is to gain confidence. And the only way to gain confidence is to take action consistently.
How to overcome it?
Embrace it. Stop resisting to it
Remove expectation and accept imperfection
Take new massive action to build a new belief
Focus on learning
Make decisions based on what you believe, even if it’s wrong. Because you will discover that mistakes won’t really kill you and it’s not as scary as you think it is. The fact is no one wins 100% of the time, even 80%. You will make some right decisions and some wrong. After all, you will build trust with yourself.
In your self development journey, self doubt is inevitable. Instead of looking at it as a bad thing, I challenge you to change that mindset to see it as a friend telling you that what you want is on the other side and you just have to take action to get there.