Though I barely edit film now (hope to get back to it in a little bit), it was my primary job for a decade.
While editing does require physical and mental endurance (and patience), the muscle it really strengthens is a kind of emotional endurance.
Film, in my opinion, is the least-mediated medium. Relative to other artforms, film plugs directly into the human emotion port. It’s instantaneous and interpretation is automatic.
The experience of editing film is the experience of playing back emotions over and over again, and the trick is being open so that you can stay freshly attuned to how your analog amygdala is reacting.
This is, not harder, but different than it would seem.
Just as your eyes adjust and recalibrate to the world through color-tinted sunglasses or ski goggles in mere seconds, your emotional response will adapt to a visual story, especially when the emotions are overwhelming in some way (probably what you’re going for).
As in real life, the best way to increase emotional capacity is counterintuitive: The strategy is to fully feel the emotions, not to suppress them.
Emotional fatigue results from suppressing emotions, not from feeling them.
So when you’re editing a moment on film that’s choking you up, or making you feel scared or excited or proud, the absolute best way to keep yourself in it, calibrated, improving, is to fully feel it.
You may feel foolish crying over and over again when you play a moment 100 times, but that’s the job.
And it’s a beautiful job.