In our self-indulgent times, telling people to diminish their Simcha is quite a challenge. Religion is too frequently accused of being a fear that someone, somewhere, is enjoying himself. Asking people to be unhappy for three weeks or ten days might be too much, regardless of the good reasons for it.
Because of this, I think that something suggested by the Lubavitcher Rebbe long ago has a resonance in our times. He asked that a siyum be made every day of the nine days, even on Tisha B’Av (on Masechta Moed Katan)!
Background: The minhag (custom) is to refrain from consuming meat and wine from Rosh Chodesh Av until the day after the fast. The exception to this rule is Shabbos, and any valid celebratory meal. Included in this category is a Bris, Pidyon Haben, and a Siyum.
A Siyum is the conclusion of the study of a Masechta of Talmud or Seder of Mishnayos.
With this background, we see that a Siyum is the only event that can be legitimately scheduled ahead of time. Yet it’s still acceptable. It sounds like a loophole.
The Lubavitcher Rebbe asked people to make Siyumim during the Nine Days. He took what people thought of as a loophole; and transformed it into a lesson in what true Simcha (Joy) is.
Yes, this time of year is set aside for mourning. Yet, he felt that even during this time and frame of mind, one should actively seek (halachically acceptable) ways of finding our simcha in those kinds of moments.