On Tisha B'Av, the yetzer hara is very strong. I don't know about any of you, but I find myself sleeping a lot through the day- especially at the moments when I begin to concentrate on the Beit Hamigdash. During one point yesterday of attempting to persevere in maintaining the appropriate focus, I happened upon the following realization.
Tisha B'Av is the culmination of the Three Weeks. During that time frame, with each passing day, we increase our awareness of the tragedy inherent in this period of the Jewish calendar. The period consequently works to prepare us for Tisha B'Av, to plug us into the state of mourning we should be feeling by considering how our sins produced the calamities that befell yiddin throughout the centuries on Tisha B'Av. More to the point, on Tisha B'Av, we refrain from all activity in order to ponder how our personal failings have kept the klal from meriting Moshiach that year, and to mourn that we must wait until the next year to potential see his coming.
The three weeks following Tisha B'Av end with Rosh Chodesh Elul. During Elul we begin sounding the shofar, and otherwise prepare ourselves for Rosh Hashanah and being judged. We consequently use the month of Elul to overcome our shortcomings up until that point and begin to do better. That the period between Tisha B'Av and Rosh Chodesh Elul is precisely three weeks suggests that just like the Three Weeks prepare us for Tisha B'Av, the three weeks following Tisha B'Av should help us lay the foundation for change in Elul. Thus the days between Tisha B'Av and Rosh Elul should be spent using the awareness of our shortcomings garnered during the official Three Weeks to start affecting the spiritual changes necessary to improve ourselves, and hopefully merit Moshiach in the coming year.