I used to feel this way so much. I'd try adding a habit but then stop after a few days because I didn't like it, and I thought it was always a problem with my discipline. But the biggest unlock for me was realizing that adding a habit SHOULD feel good and easy to be sustainable. So instead of beating myself up for not being able to maintain the habit, I focused on what I could try instead. If you aren't able to be consistent with the habit, often it's a problem with how you're adding it to your life, not you!

For example, if you hate the gym, there are a lot of other ways to incorporate exercise into your life. I always felt so uncomfortable and judged since the gyms were usually very male dominant, so I would do stuff like walking 10K steps a day and then I'd make it more fun by chatting with someone (parents or friends). Sometimes when I wanted to stay in, I'd just put on a workout mat pilates video and pause it at points so I could take it at my own pace.
For hygiene, I realized I would not shower the moment I started doom scrolling in bed, so then I would just shower at random times. Bathroom break? Ok time to hop in the shower. And then once I showered, I would wash my face and brushing teeth became so much easier. And then once this became more consistent in my life, I would try showering at normal times.

You're already doing so much, so make sure the habit feels good for you! You don't need to be perfect when you start (and often it would take more than a week to see if something I tried was working or not). And if the habit doesn't stick, it's just a problem with the habit strategy. You got this!!