I’ll echo much of the advice posted so far, with an emphasis on things you can do that can have low barriers: exercise, starting with walking with occasional speed-ups; same sleep and wake times every day; set limits on your eating, like only within an eight-hour window; and call around looking for a therapist that clicks. I can talk to just about anyone (rambling to a disinterested third party so as not to burden my friends and family is half of why I hire a therapist), but others may be more selective.
Some other things that have helped me crawl through and out of anxiety and depression:
Cold showers, because I feel so much better afterwards, and it’s a way to do a low-stakes difficult thing and thus build confidence to just go for it. Saves water and energy, too.
The Blindboy Podcast, because I enjoy his stories and his mental-health journey expositions. He sticks to his experiences, with which I have much in common.
WOOP: wish, outcome, obstacle, plan; rather than stop at the good feelings from a daydream, consider the obstacles and make a plan, each step in as few words as possible. Not my idea—-German psychologist, I think.
If you don’t already, breathe through your nose, if able (Breath, by James Nestor). Since I’ve been taping my mouth shut with a narrow strip of surgical tape I’ve been sleeping better, waking up to pee less often, and not losing so much water overnight, so I wake more-ready for the day. When I feel an anxiety spiral approaching, my best chance of interrupting it is by focusing on my breathing. A cold shower will do this for you, and then you keep it going. Wim Hof has some useful guided breathing narratives on that popular video site that Google bought awhile back.
Humming and singing are ways to create ephemeral art and stop the internal voices of negative self-talk and immature mantras [edit: intrusive thoughts].
Tiny Habits, by B.J. Fogg; even if you remember that you forgot to practice yoga, smile and pat yourself on the back for remembering.
So much to try!
Forgive yourself for stumbling through life, for making mistakes after mistakes, for not sticking to plan, for letting yourself down, for indulging, etc. Intrinsically you are better than no one, no one is better than you, and you are worthy of love. What does it feel like to practice unconditional love for yourself? What does it feel like to be thankful to yourself? To others?
Edit to add: Blindboy ep153 is mostly about mental health, and there are numerous other episodes with that focus. This one has a reminder about the importance of compassion for others as a way to practice it if compassion for yourself is difficult. Also, imagining yourself time-traveling to visit your younger self during times of stress, and practicing being a good parent to yourself in those moments. I like this one as I work on not passing along my avoidable traumas to my child. Going back and simply sitting there with my confused, emotional younger self is a way to dissolve some residual stress.