How do you overcome these kind of thoughts?

Well, you’re right: there is no guarantee that the first time you do something that you’ll definitely succeed. But if it’s the first time you’re doing something, isn’t it a bit of a big ask to expect yourself to get it right first time?

When a baby is learning to walk, does it just start walking smoothly straight away? No! A baby allows itself to try, try and try again. It learns from the early wobbles; learns ho to adjust and re-balance until after practising for a while, despite all the early wobbles and falls eventually a baby learns to walk – and even run! Failure isn’t a problem; failure is literally part of the learning process. Failure is part of the process of becoming a success.

What is failure really? It’s just the wobbles at the beginning of your learning process as you learn to walk this new path. Once you start TRYING, only then can you get a feel for how to course-correct, but you have to start if you want to succeed.

If you don’t even try, you can never succeed. Sure, you’ll be safe in that you don’t experience failure in that field… But if you don’t even try going for your dream, what will you be doing instead? Something you don’t really want to do? And you’ll always have that “What if…?” hanging over you? What’s the point in that when you can try to do something you REALLY want to do?

If you try following your dream, you may not succeed right away, but the more you practise and go for it and persist – the further along you are on your journey towards success, and the more likely you are to succeed. With every attempt you grow wiser and learn more and more. If you’re committed and determined, you will see success eventually – it’s just a matter of time. Look for a way until you find a way.

Put aside all your limiting beliefs, and put aside all the things nay-sayers are saying – don’t listen to them. Just say: “I don’t care what anyone says, I’m gonna do this; I’m gonna figure it out; I know that there’s a way to figure it out”.

Just decide: I don’t care how many times I fail before I succeed – I’m gonna do this.

Success is slowly moving towards something that we really want and love. So choose what you want and start moving towards it!

References
What if I fail? by Aaron Anastasi https://www.youtube.com/watch?v=P7g3EqRmyyg