. . . might be, “Yes, you can.”
The person who says she can’t do it really believes she can’t do it; she isn’t lying. Telling her she can do it doesn’t change her belief.
Experience changes beliefs.
A much better response to “I can’t do it,” is to find something she can do. Then something a little more difficult, and then a little more difficult, until finally she’s able to do the thing she thought she couldn’t do. Then the cycle repeats.
(Another terrible response to “I can’t do it” is punishment: “do ten push-ups every time you say “I can’t.”)
