The realization that I had hit a wall usually came late at night when I looked back upon the work I either was or was not producing. Or it came as I faced a bout of unemployment and I looked at my book, and my future prospects, with despond.
I think most people, regardless of their profession, have spells where they feel like they've reached the end. A lanky pitcher might have seven or ten games in a row where he can't find home plate, or he's lost a few miles-per-hour on his heater. He gets shelled repeatedly and he ends the game in the showers, staring down at his hands wondering "where did it all go."
The trick to lasting, as I seem to have lasted--at least so far--is the same trick you need to do good work: keep coming back with something better. That is, when something dies, or gets slaughtered along the way to approval, don't give in. Keep trying to win.
Or, in the succinct words of Steve Hayden, "the best revenge is a better ad."
My two cents say that career setbacks--regardless of their cause--happen to nearly everyone. As above, "the best revenge is a better job."
Somehow--whether it's reworking your book, or trying to jump-start your career via freelance--you have to find a way to rejuvenate yourself. You have to make a u-turn to get out of a dead-end.
Not for a second do I think any of this is easy. And there will be moments, probably, maybe weeks or months, where fear, depression and anger may also be your enemies.
But, whatever this means, quoting Lady Macbeth, "...screw your courage to the sticking-place / And we'll not fail”.