Some possible answers that haven’t seemed to have had large effects on hard-workingness for me:
Switching roles (to the extent that this doesn’t come with one of the above factors).
Medication. (ADHD meds had a very sizeable short-term effect, but not a persistent one.)
Internal work.
Productivity hacks.
Exercise, diet, and sleep.
(Several of these had important impacts on my mood.)
Some possible answers that haven’t seemed to have had large effects on hard-workingness for me:
Switching roles (to the extent that this doesn’t come with one of the above factors).
Medication. (ADHD meds had a very sizeable short-term effect, but not a persistent one.)
Internal work.
Productivity hacks.
Exercise, diet, and sleep.
(Several of these had important impacts on my mood.)