I can't think of anyone I admire who isn't fuelled by self-doubt. It's an essential ingredient. It's the grit in the oyster.
If you can't pay for a thing, don't buy it. If you can't get paid for it, don't sell it. Do this, and you will have calm and drowsy nights, with all of the good business you have now and none of the bad. If you have time, don't wait for time.
It's one of the most liberating things I experience in writing - letting yourself get rid of a gesture or character or plot point that always nagged, even if you couldn't admit to yourself that it did.