I hear you and feel you on this being a hard (hardest) pill to swallow, and I think I have a helpful phrase. It helped me quite a bit so I hope it helps you:

'For the love of the game.'

When you don't make any money and no one comes to your shows; when the booking emails go unanswered and the likes on soundcloud remain <10, just remember why you picked up the instrument in the first place. For the love of the game.