I've had some similar experiences, found myself saying some of these exact same things.

'I know these things; but they don't help.'
'If I could do those things, I wouldn't be here looking for help'

I've had a lot of frustration with receiving those same stupid responses, that eventually boil down to:

'Do the thing you can't do anyway'

That said, I can't say for sure that these things don't work. Maybe they don't work for some people; it just seems that in light of some of the issues I have to face in order to do these things in the first place, it becomes a ridiculous catch 22. I have to do it in order to be able to do it? What?

Or you know, the common factors of Anhedemia (lack of pleasure and motivation) and antagonism (heightened resistance to change, attachment/protection of problems or defense mechanisms) I've entrenched myself in might have something to do with it. Which is why hearing 'Think happy rainbow butterfly thoughts!' generally makes me want to punch somebody.

The only thing I've found that is sometimes effective revolves around accepting my 'negative thoughts' as part of me, my 'weaknesses' as just misapplied strengths, and not trying to change them; instead, focusing on applying my strengths to compensate, listening and responding to negative 'voices' objectively/kindly, and focusing on what I can do to overcome those things instead of trying to repress or 'change' them.

...Again, though, it seems to just happen when it wants to, not really something I can turn on and off.