I'm not sure you have to lie to yourself.
Have you heard of radical acceptance? DBT skills may help you find a way of accessing the means to who you really wish to become through you and not another person.
When I get manic I also think in my euphoria that my connections to the world will alleviate untold suffering to millions. I do follow through quite a few of my manic creative decisions but unfortunately depression usually negates my efforts.
TBH I still look for external reason to be validated otherwise why post here? And then panic because I think i've written bull s**t and everyone thinks I'm a moron.
Usually I want to kick the doc who says I have great inner strength and I'll be fine, because at the time well I just don't believe it.