@smhtimson having gone through burnout multiple times earlier this year, here are some things I tried:
1. I stopped mind fucking myself about how burned out I was - - instead of "ah, fuck, I didn't get enough sleep, I'm already so burned out, and now my sleep's fucked up, I'm so screwed", just establishing a rule like "hey, if its more than 5.5 hours, I'm good" "hey, if I ate healthy for at least 4 days this week, it's all good" - - - that helped me take the boot off my own neck.
2. I also have an ageing parent to take care of, and this definitely weighs on me, but I forced myself to accept the fact that I had to first get my own shit handled, before worrying about them - - and if "getting my shit handled" meant taking a few weeks off from work, that was fine. I used to try to motivate myself by thinking about all the people who depend on me that I'd disappoint - - and this works 90% of the time, but not when I'm burnt out. When I'm emptied out, then I've found a little self-compassion can work wonders. I also took my dad on a week-long vacation. Of course, parents value their kids supporting them financially etc, but they also value having a good relationship with their kids. Money is one of many ways you can take care of someone.
3. I got myself excited about learning a new skill: coding. I would sit down for a couple hours everyday with leetcode problems, just because. Just for the joy of problem-solving. I put aside all thoughts of "how can I use this" or "how long will it take before I get ROI from this" - - these are great thoughts to have 90% of the time, just not during burnout. Learning a skill just because it was interesting and challenging, with no external outcome whatsoever, helped me a ton.
4. I got back to reading fiction again, put the self help/business/marketing books aside for a few weeks. I was so burnt out that just reading a business book or listening to a podcast would put me into a shitty mood because of all the things I could do but wasn't doing etc.
5. I cut out around 60% of the things I was working on. I stopped working on niches that didn't have high ROI. I stopped working on services that were volatile. I made my mind up to not work on any business product/service idea unless it was an evergreen one. No more "let's find a loophole on X platform and exploit the shit out of it for 2 weeks" - - I'm just too old for that shit, I'd rather work on things that take longer to build, but also last longer. I also got VERY realistic with my goals and what I was aiming for. I used to think I would be amazing at pretty much everything if I just tried hard enough - - this is a great mindset to have, but it misses out on the fact that its much more feasible to just get really good at a few things. Once you're a couple years in, it's better to streamline, prune out everything that isn't working.
6. You mentioned 3 failed businesses. I've had 2 failed businesses (not marketing, one was a physical product manufacturing thing, the other was a niche technical service) in the past 7 years, and I've learned to joke about my current marketing business as a "not-yet-failed" business. Looking back, a lot of my prior business failures were the result of not giving the appropriate amount of attention to every aspect of a business. I would over-invest in product/service fulfillment and not pay attention to good customer service. My lead-gen was messed up and disorganized. I had way more ideas than I could implement and test. I didn't understand my customers well enough...etc etc etc. Your failed businesses will give you TONS of data on what you can improve in your processes, data you will never get from books or courses because it's specific to you and your working style.
7. Baby-stepping helped me slowly get back into work momentum. Chunking down tasks into smaller and smaller and smaller ones until they didn't feel daunting at all. Instead of "make a landing page for XYZ" I would make tasks like "think of a headline for a landing page for XYZ" just to slowly get myself into the mood again.