Another reason to spare your toddler the lecture...

He or she is more than likely not listening or doesn't understand a thing you are talking about.
I was driving the other night with my girls and small fry was telling me what letters she saw on the radio on the dashboard.  She wanted me to point to them and I finally figured out she was reading these tiny letters on a knob.  I said, "man you can read those-you must have really good eyesight.  It is probably because mommy fed you all those carrots when you were a baby."  She said, "But I don't like carrots."  I said, "I know you don't now but you used to love carrots and carrots give you good, strong eyes to see.  That is why you should eat your carrots so you can have good eyes, but since you don't want to eat carrots any more I guess you can have bad eyes, " to which she replied, "mama-I don't have bad eyes, I have blue eyes."  Enough said, the lecture was a complete miss, grin and bear it mom.  Save your breath.