Your english is better than the english of a lot of native speakers.

I doubt it.

"You know what? I'm not mentally ill. I just need to improve myself."

Who cares about mental illness? There's action and inaction. Action WILL lead to something and if you do it well you'll get GOOD results.. Inaction gets you nothing no matter what you do.

Also, "keep it simple, stupid" is only helpful when the problem can be simplified further.

No, it's always useful and is a good way to think about things in general. Why should things be more complex when they can be simplier? Do you begin with a simple (or rather, minimal) model and later expand on it or just build a complex theory and try it? The time investment, effort, and return are way better on the simple route, the complex route sucks because by the time you do both you WILL get a sharper pencil using the simple way.

You should also remember that complex things are built out of simple things, so you won't be a complex master before you're a simple superhypermegaultragrand-master.

Simplifying things is really hard when we don't understand them, and mental illness is one of science's big question marks.

I think I need anger control.