Or any skill that you deeply value for how it helps you, but maybe easily overlooked by an outsider?
I think exercising atleast 2-3 times a week was good for me. Not that I look much different, but I do feel a bit stronger and that is nice. Neck isometrics and bridges too. They really helped with balancing looking at mobile or PC screens.
Learning some keyboard shortcuts was nice. The major one would be Win key + Arrow keys to manage multiple open windows/apps.
Then, finding that I can add commonly used options to the QuickAccess bar in Excel, Word etc. Libreoffice would probably have similar options too.
Its hands down my most useful tool, especially as I can both invite people to my events and I can share my calendar with people I choose. Everything goes into the calendar, from appointments to birthdays to holidays to when things need to be renewed. Only time I forget something now is if it hasn’t gone into the calendar.
I especially like being able to send the address of where I am meant to be going straight to my maps program, as I will usually try and work out where I want to park when going somewhere. Saves so much hassle when you actually get to the event.