Stop eating sugar
A woman once came to Mahatma Gandhi with her little boy. She asked, "Mahatma-ji, tell my little boy to stop eating sugar."
"Come back in three days," Gandhi instructed the boy's mother.
After three days, the woman and her son returned to see Gandhi. He looked at the little boy and said, "Stop eating sugar."
The woman asked, "Why was it necessary to wait three days for you to tell my little boy that?"
The Mahatma replied: "Because three days ago, I hadn't stopped eating sugar."