There have been many life-changing Linux moments for me, but most fade into my backstory as they become the status quo. There's one little keyboard trick Linux taught me that I'm reminded of every time I use it (maybe 1,000 times a day), and that's converting the Caps Lock key to Ctrl.
Always wondered if you change the keyboard layout in order to use the caps lock key as the escape key or if there is another way to map it.