Maybe your exercise can be to direct your thoughts elsewhere. Start with 5 minutes instead of 30 and actively try to think about something else when your thoughts become too negative. I can't guarantee it will help you but it's a sort of meditation that's worked for me when I felt like my brain wouldn't turn off.

Sounds like your body is telling you something?

Time to find support that you trust and face whatever is going on under the hood.

For me, the three major turning points were quitting my job, later starting somatic therapy with the right therapist, and then finally getting diagnosed with ADHD. Good luck to you :) wish you the best