I’ve heard it described this way (and I wish I could remember by whom, so I could give credit):
When you exercise, picture yourself making a small, one-time deposit in the bank of your health. A single afternoon jog will not make you healthy, but consistent deposits over time add up.
If you miss a workout or eat a donut, you have not broken the bank, closed out the account, what’s the use of trying anymore. You simply made no deposit, or you chose to make a withdrawal.
You’re usually dealing in small transactions over time. Smaller than you think.
Creative work is the same.
Miss a writing day, you missed a deposit. You can still make one tomorrow.