As a counter to the post putting it rudely, I'm going to try to say what's helped me more nicely. Arguably could be summarized similarly.
If you can, get medicated. It's not a fix-all, and it may take time to find the medicine and dosage that works for you, but I have a lot more success in "adulting" when my brain chemistry is functioning closer to "normal".
Beyond that, try to start accepting any headway as headway. If you can, force yourself to do one thing that will take less than five minutes, and do it right now. Even if it's as small as putting one piece of dirty laundry in the dirty clothes hamper, it's something. Do your best to stop the internal negative self talk that it's not enough. If the alternative was you paralyzed doing nothing, then doing even a small thing is a positive step. Whenever you start spiraling about everything in between where you are and where you feel you should be, try to stop yourself and do one thing that you can do in five minutes or less. No one just leaps to the finish line.
Any progress is progress. If you've ever seen Gurren Lagann, to be cheesy, every small turn pulls the drill forward just a little further.
It's not easy, but if you keep trying you will eventually build habits. They will be far harder won, and far easier to lose, but you can. Most importantly, even if you don't, you will still be in a better spot for trying. Any progress is progress.
And if you mess up, you just messed up. It's not some grand failure in a chain of failures that somehow defines you. That's just negative self talk. There's plenty of people out there managing life worse with far less exacerbating circumstances, I guarantee it. Just keep trying.
Again, far far easier said than done. But just start with any small movement forward you can muster. Then do the next tiny movement forward that you can. And the next. When I'm in a bad state I really really try to focus on the smallest things.
I ate within an hour of when I should, even if it was junk food. I put one glass in the dishwasher, so that's one less dirty one lying around. Etc.
Anecdotally, something I've identified in myself and numerous others I've known with ADHD is the terrible trap of comparing yourself to an idealized concept of yourself.
"If I could just get my shit together, I'd be like this. So I need to work to be like this. But I'm not like this because reasons reasons reasons spiral spiral spiral"
"I know, tomorrow I'll start fresh and tackle all of this as the idealized version of myself that doesn't have motivation/focus/executive processing issues"
If you lost an arm, you wouldn't make plans to take care of things tomorrow with both hands. So don't assume you'll be worthless, but also don't assume you'll magically be motivated to do everything all at once tomorrow. I fall into this trap all the fucking time.
Stop. Take a deep breath. You aren't competing against yourself in perfect conditions, with all your shit together. You aren't competing against your peers and the idea of how they work through a filter of your own eyes where you can't possibly know everything about their situation and internal thoughts.
You're competing against yourself as you are right now. As you were five minutes ago. As you were yesterday. Try to take time and figure out how you specifically work. Identify your limitations and struggles, doing your best to self reflect honestly, without the added failings from depression speaking, and without the added ideas of how good you "could" do. You. As you are. Now.
Then try to structure things in ways that work for you. Not the rest of the world, not how your parents thought things should work, for you and the way you operate right now.
Accept your flaws and personal quirks instead of fighting a constant head on push against them. Work with them, around them.
Then eventually you can start working as often as you can (once a week, once a day) to scoot back the edges of those limitations inch by inch. A lot, maybe most, you'll be stuck with and have to find ways to live with and around over time. Some you can overcome.
But the most important thing is to just try to do something small you can do right now, and accept that any progress is progress.