The Rebbe acknowledges his letter about 19 Kislev, Rabbi Schneur Zalman’s liberation day, emphasizing it as a “new year” for Chassidus—serving G‑d joyfully with body and soul, following the Baal Shem Tov, without self-affliction or excessive austerity.
https://www.torahrecordings.com/rebbe/igroskodesh/016/004/5967