Years later, a teacher’s random comment will echo in your head at the exact moment you need it.

You store far more than you choose to. A teacher says eleven words on an ordinary Thursday, you do not even register them properly, and they sit somewhere for nine years until a situation turns up that they happen to fit. Delivery is delayed, and the date is unpredictable. That is also true of what you say to other people.

Write down the lines that land, when they land. Then be generous with your own: say the encouraging specific thing to someone younger than you, out loud, and accept that you will never know whether it took.