Reb Yisroel Deren relates:
As a thirteen-year-old bochur, I asked the Rebbe whether to do a particular practice. The Rebbe answered that I should, if I am ready to take upon myself a certain condition.
It was quite a difficult thing for me to undertake, and at my fourteenth birthday yechidus, I asked the Rebbe what to do.
The Rebbe read my note, and without looking up said to me, “I already answered you. Will you do it or not?”
The Rebbe continued looking down at my note, waiting for my response. I stood frozen. Finally, with tremendous effort, I hesitatingly gave the Rebbe a nod.
The Rebbe looked up with a smile, and said, “If you will remember that you promised me, you will surely be able to accomplish it.”
(A Chassidishe Derher, Issue 70)