I've never been able to properly fake it. Well, I've faked being 'ok' but I'm incapable of faking anything more exciting than that, lol.
I know people here are posting their bad experiences and it's true you shouldn't keep things inside... but I do believe there is some truth in 'fake it til you make it', because to an extent faking it could build your confidence, and they do say that if you for example fake being confident, you will eventually stop faking and just be confident. Not sure how it works, but I've got a book written by a life coach and she recommends it.
I do wish I could fake it. At least things like confidence, because I get so anxious and I can't hide it, so then I'm even more anxious because I realise how much I'm sticking out. If I'm out of the house I'm grasping onto my mum and hiding behind her in shops. If I could fake it then I would be able to at least pretend to be confident and talk to people... and the more I did it, the easier it would get, until it would be real. Maybe?!