B"H, 7 Menachem Av, 5713. Brooklyn.
...Regarding what you began in your letter about missing one bath, surely you did not lose but rather gained. As I wrote to you in my letter, if I recall correctly, our Sages say: 'Shabbos is for refraining from crying out'—and nevertheless, and specifically through this, healing is close to coming. And it is even greater than the healing that comes through bathing, as is understood...
Summary
The Rebbe teaches that sometimes what seems like a loss—such as missing a bath on Shabbos—actually brings about an even greater benefit and healing. Trust in the spiritual process and the unique blessings of Shabbos.