The period between the Seventeenth of Tammuz and the Ninth of Ab is called "Yeme Ben Ha'mesareem", which literally means "the days between the narrow traits". The term is taken from one of the verses of the lamentations in Meghillath Ekha, which we read on the ninth of Ab: "All her pursuers overtook her in narrow traits" (Lamentations 1,3). The word "Mesareem" (narrow traits) can also be interpreted as distress. Hence, we can understand this verse from a different angle: "All her (the Jewish nation's) pursuers overtook her during the days of distress". Days of distress are the twenty two days between the Seventeenth of Tammuz and the Ninth of Ab, which are known to be times of great sorrow and affliction for the Jewish people. Many tragedies and calamities befell us throughout our history.
Our Rabbis of blessed memory, based on the Kabbala, explain that these days have another deep meaning. The word her pursuers in Hebrew (Rodfe-ha) can be divided into two separate words: "rodfe" and "Y-ah"-- those who search G-d. It is during these days that we can truly search G-d and find Him! This is the time to consciously make an effort to connect to our Father in Heaven.
How? Through focusing on the needs of the Jewish people as opposed to our own personal needs. Rather than feeling pity for ourselves for not being able to wear new clothing, we should focus on the lack of a temple and the destruction of Yerushalayim. Instead of feeling sorry for not being able to swim during the nine days (between the first of Ab and the ninth of Ab), let us pray for the redemption to take place.
The more we think and pray for the Geulla (redemption) of our Jewish people and the pain of our Father in Heaven the closer we get to Him. This way we will become "Rodfe Y-ah", those who truly search G-d and find Him. In this merit may we see the coming of the Mashiyah speedily in our days, Amen!