Bonus: none of these are location dependent. Work in a coffee shop? You can do this! Standing desk? Sure, you hipster douchebag!* Hunched up on your bed with your laptop? All this shit fits on a nightstand, next to the lube and that serious book you want your one-night-stands to think you’re reading.
Tennis Ball. Use it for self-massage, releasing whatever that shoot pain in your hip is, rolling your probably overworked forearms and hands on, and throwing at people. Really, for a couple of bucks a can, you can’t get a better multi-tasker. Plus, apparently there’s a game you can play with them or something?
Water. Not coffee. I’m sorry, coffee, you know I love you, but you are not a replacement for water. Bonus: drinking more water makes you retain less water, so you feel less like a bloated sack of crap when you leave your desk to go be human among the humans for a while.
Fitness Tracker. Entirely unnecessary, but it does add a certain “futuristic cyborg” element to the day. Mine reminds me to move occasionally, presumably because it thinks I’ve died. My selection process boiled down to “this one looks the least like shit, so I’ll probably actually wear it.”
Eye Drops. Working at a computer leaves me with eyeballs that feel like marbles covered in sandpaper and then dipped in hot sauce. Get some drops so you can stop peering at people like you were just accidentally awoken from cryo-sleep.
*I did the standing desk for a while. I liked it, but found that it only worked for certain types of work. First draft writing was great, editing not so much.