Sometimes when I am too tired, I lean back in my chair and click through Hacker News or something similar. I use Vimium in my browser and HN is great to navigate with it, but that's the not the point - the whole point is I don't want to sit above my keyboard with my hands on the home row.

I consider myself a "keyboard power user" if this is a thing anyway, and I really dig the home row thing (Vimmer for 20+ years now), but frankly having my hands on the keyboard ALL the time throughout the day is really tiring. So, I actually like my mouse for a change of posture, the cursor that I can follow with my eyes, etc.

P.S. I have to admit, though, that I love even more the interfaces that don't require a mouse in the first place. It's a shame we stopped adding well-thought tab stops in the UI and keyboards shortcuts are just a free-for-all in the apps.