I see a change in me when I stop the negative self-talk

Drive a mile with the handbrake half on and the car still gets there. It just costs more than it should, and you spend the journey wondering why the engine sounds like that.

Running commentary of the hostile kind works out about the same. The work still gets done. It takes a third longer and leaves you far more tired than the task alone would explain, so you conclude the task was hard.

Let the brake off for one afternoon and the thing people usually notice first isn't happiness. It's that they're less tired at six.