My DS1 has times where he says he 'can't do it' when I know perfectly well he can and he chucks some doozies of tanties. I'm trying not to argue with him 'cause that doesn't do any good. I say well you try & I'll help you if you have trouble. He seems to be getting better of late (touch wood) so it may be a matter of riding it out and pre-empting the trouble if you can (having said that I'm not very good at that). Hopefully someone else can offer better advice.