Whenever my young children say, "I can't do..." I tell them that they are right. If they tell themselves they can't do something, the result is that they can't. They say it is so and their mind believes them.
Instead I encourage them to ask for help or guidance in how to do something. It might be as simple as showing them how to use a step-ladder to reach something (as long as they are not in danger of course). It is easier to do something for a child than teach them how but in the long-term the latter is kinder and more useful. As the saying goes, "Give a man a fish and you feed him for one day but teach him how to fish and you feed him for life".
I have a male friend who is the eldest of three brothers. Whenever something needed fixing in the house, their father would do the job. The result is that all three of them are hopeless at DIY and now their father has passed away, they have no one to help so must pay handymen whenever necessary. It would have been much better for the father to do the job but with one or more sons watching and encouraging them to do at least part of the job themself. We learn through trial and practice.
As well as eliminating "can't" from our everyday vocabulary, another bad word is "try". When you say you will try to do something, it sets up a message to your brain that you might not do it. I tell my children not to try but to do their best or at least have a go. Sometimes they have never tried to do something or stretched themselves eg opening a plastic bottle. I show them how to use a handtowel to gain a better grip on the bottle. They might not have the physical strength but I encourage them to use the technique so that when their wrist is strong enough, they have learned this little piece of independence.
"Do or do not. There is no try." - Yoda
As a hypnotherapist, I listen carefully to what people say about themselves and particularly the "I can't.." and "I try.." Often that is just the problem. They are saying the wrong things to themselves and their minds keep hearing the wrong messages. They must not be surprised if they keep receiving what they do not want.
Antonia Stuart-James is an English Hypnotherapist in Belgium helping people make positive change.