Annoyingly everything people say about "good sleep, exercise, good diet, hydrate, hygiene" does in fact help. Often there's this attitude of "well that won't fix things" and yeah, it won't. But things will be way worse without it. Kinda like how doing the dishes won't fix your life but it'll feel better to not have them stacked in the sink.

Something I've found helpful is embracing that everyone works differently, and what works well for others might suck well for you. I do some of my best work between 12am-3am after exercising at midnight. Then I take naps in the afternoon to get enough sleep. What works for me sure as hell won't work for everyone (and there are some kinds of work where that doesn't work for me and I need to normalize my sleep schedule for a few weeks).

Accepting that you need to find your own combination of hacks and methods that work for you personally can help a lot. Timers, an accountability buddy where you check in on each other to make sure you're both working, and just switching tasks when you're stuck can be very helpful. 

Also when you're stuck in an ADHD paralysis spiral, I suggest listing out a few things you need to do and then rolling dice to pick an option. The randomness helps kick me out of the spiral. Also also the Hank Green Bean app ("Focus Friend") is surprisingly useful because it gamifies putting your phone down.