I spent a bit of time this morning doing the usual peruse of the internet and twitter and came across this video - I feel like i might have heard it before - I listen to a lot of This American Life podcasts - but the video I'm mentioning is a clip of Ira Glass talking with some animated typography.
Its about writing but essentially its also about creative work. Have a look...
I'm probably still fairly early along in years compared to some other lettering artists out there - i was self taught and a late starter I should explain - but this soundbite pretty accurately summarises the last few years and the continued progress - you're surrounded by work from others that you know is great and you certainly aspire to a similar greatness but you never quite manage it.
I can only say that you get closer with each practice. Give up and try something else if you want - the world needs all of the people who do non creative work as much as anyone else, but if you have the commitment to keep trying at this, then rest assured that whatever happens, you will at least get better at it.