You sound desperate. If you are, I have a suggestion that will help. But you'll only be able to do it if you are desperate:
Set doable goals, do them, and celebrate them.
1. Start off with clearly doable goals - no challenging or stretch goals! A good guide is to estimate what you think you can do, then halve it. [note: if it turns out that you can't do it, it was not a "doable goal" - start again with an easier one] To give you an idea of just how easy I mean, an example is: to make a mark on a piece of paper.
2. Doing them means to remain focussed on them. No moving the goal posts! Don't be distracted by other tasks; nor by thoughts of whether you can do it or not, nor by whether it's too easy etc. The way to prevent distractions is as in meditation: acknowledge them without anger nor fighting them, and gently shifting your attention back to the here and now.
3. celebration means something very specific: you recall (visualize) the state of events before you began; and then you compare the visualization with how things are now. And you notice that there is a difference - a change in the world - that is entirely due to your power.
The key is self-appreciation. You thought I was melodramatic when I said you can only do this if you're desperate? No. Setting a reasonable goal, doing it, and celebrating it is really that hard. It requires a particular kind of self-discipline that (according to your post) you presently don't exercise. You can improve at this - if you're desperate enough.
every great achievement is made up of a number of small achievements