There is a vitality, a life force, a quickening that is translated through you into action, and because there is only one of you in all time, this expression is unique.
If you block it, it will never exist through any other medium and be lost. The world will not have it. It is not your business to determine how good it is, nor how valuable it is, nor how it compares with other expressions. It is your business to keep it yours, clearly and directly, to keep the channel open.
You do not even have to believe in yourself or your work. You have to keep open and aware directly to the urges that motivate you. Keep the channel open. No artist is pleased. There is no satisfaction whatever at any time. There is only a queer divine dissatisfaction; a blessed unrest.