Trust is a track record

You want the doctor with experience, not the one doing his first brain surgery.

Nobody wants a first-time pilot, or skydiving instructor, or tattoo artist.

Trust comes from a track record.  If you have imposter syndrome or stagefright, it’s either because you don’t have the track record yet, or because you keep forgetting about it.  In both cases the solution is the same: build your track record until you can’t ignore it anymore.