Therapist. See a therapist. They quantum leap your process if the right therapist is chosen.
Also, read the first chapter of "Seven Habits of Highly effective people".
- Power one line sentence there: "Make and keep small commitments". Develop integrity, but for small tasks.
Small being subjective to you i.e. you feeling you cannot brush your teeth, and you often do not. Write in a planner "Touch toothbrush/ brush for 5 seconds". Its not a trick, literally do what you said you would do in your planner. Nothing more.
Keep doing that for various things i.e. cannot study, then study for "1 min". And again don't do more.
Tick things off, and inevitably you'll develop more self-trust, and confidence that when you commit to something that you'll do it.
It gives you a level of hope for the future, and inevitably what you'll perceive as small will increase.
Its not sexy, but it works.
It is similar to the therapeutic method of "behavioural activation".
It won't solve everything, not close. But relative to being without the method it is incredible.
There's a lot of airy-fairy advice on depression, or things like meditation are recommended. But if you don't have the motivation for meditation then you won't meditate. Build the foundation through building your integrity.