Tikkun Hatzot During the 3 Weeks
There is an established Minhag to recite Tikkun Hatzot after midnight throughout the year. This is especially true during the three weeks. In addition, during the three weeks, there is another Minhag to recite the Tikkun Rahel portion of Tikkun Hatzot after mid-day (except for Fridays, Shabbatot, and Rosh Hodesh). Ideally, it is to be recited while sitting on the floor.
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Due to Daylight Savings Time, Hatzot begins very late in the lunch hour. For example, in Chicago right now, it's at 12:53. Due to this and other factors, I find that it is not an easy task to do. Even though Tikkun Rahel is relatively short, I try not to rush through it, since I believe that doing so defeats the purpose. Furthermore, I try to do it on the floor. There were times that I needed to recite Minha by myself at work, but an empty conference room is much easier to come by later in the day.
Those who are able to say Tikkun Hatzot day, night, or both, Hazak Uvaruch and Kol Hakavod.