I would like to jump into this discussion. Some good ideas already.
Using 'not' in a sentence such as 'I am not stupid' sounds as though we are being good to ourselves. Unfortunately the brain does not hear/recognise 'not' and registers that I am stupid. So if you are having and argument with someone who calls you stupid and you respond with 'I'm not stupid' your brain thinks yopu are agreeing with the other person.
Quirky, I know you have mentioned saying what you can do and this is the way to go. I remember standing in my kitchen and saying 'I am not useless' and feeling terrible. Then I remembered to change my words. I said I was clever, or something of that sort. It felt like a bolt going through me. The positive words triggered a chemical reaction and wow.
For me this means I can accept I am unable to do certain things but that I am competent in many other areas, as you were saying Quirky. Apart from the futility of two people having a conversation of "You're silly" "I'm not silly" which gets nowhere and encourages anger, the second person is slowly being convinced of their silliness. Such is the power of words.
We parade our faults to ourselves and others and believe this encompases all that we are. Positive statements such as I can drive well, I can knit and sew, I am a good mother etc, start to reverse the brainwashing we do to ourselves as well as allowing others to define us. We can get so far down this road that many people give up and accept their inferiority.
So think about what you want to say and how you phrase it. If someone has to wait a couple of seconds for you to answer, so what. You can answer in a positive manner and start your journey back to wholeness.
Language can mess up even the best intentions.
This is a poem written by Les Murray.
The Meaning of Existence
Everything except language
knows the meaning of existence.
Trees, planets,rivers, time
knows nothing else. They express it
moment by moment as the universe.
Even this fool of a body
lives it in part, and would
have full dignity within it
but for the ignorant freedom
of my talking mind
From Poems the Size of Photographs 2002
So girls and boys, let's move forward with a faster pace now we know how to combat some of our stumbling blocks.