There is a famous story that Gandhi  told of himself and the girl who was addicted to eating sweet foods.

The story goes that a troubled mother one day came to Gandhi along with her daughter and explained to Gandhi that her daughter was in the habit of eating far more sweet food than was good for her. Please, she asked, would Gandhi speak to the girl and persuade her to give up this harmful habit? Gandhi sat for a while in silence and then said, ‘Bring your daughter back in three weeks’ time, and then I will speak to her.’ The mother went away as she was told and came back after three weeks. This time Gandhi quietly took the daughter aside and in a few simple words pointed out to her the harmful effects of indulging in sweet food; he urged her to abandon the habit.

Thanking Gandhi for giving her daughter such good advice the mother then said to him in a puzzled voice, ‘Still, I would like to know, Gandhi, why you did not just say those words to my daughter three weeks ago when I first brought her to you?’

‘But’, explained Gandhi in reply, ‘Three weeks ago I myself was still addicted to eating sweet foods!’