At a glance, I'd say it sounds like the things your working on are not really the things you want to work on, so you should stop and find things you actually like (that's not always easy admittedly

).
There are many things I've started that I felt like I
should do, that didn't make me happy in any way, and made me feel bad for not really wanting to do them; cutting them loose was almost always the best choice I could make because it freed up space for things I actually wanted and couldn't see before.
That aside, your brain, your emotions and your focus are all the same as muscles (or habits if you prefer that analogy); if you use them well they get stronger over time, if you don't they get floppy. So, feeling like things are falling apart (they are not) or feeling jealous of what you cant do (what other people do is nothing to do with you); that suggests you have floppy emotions

You cant force your brain to do what it cant do, or what it does not want to do. You can work with it though, its not fixed.
How you actually do all that though is something you have to figure out for yourself. Some people meditate, some people read psychology books, some people go mountain climbing. Knowing you want to change is a good step, but its also very easy to make a thread asking for advice; the actual work of doing it though is all on you