Every night between Pessach and Shavuot, the Jewish world has the biblical obligation to count the Omer. See Parashat Emor (Leviticus 23:15) ! Every Jew has to count for himself.
The Omer period can be referred to as a spiritual preparation for Shavuot (receiving the Torah). In his great book “For the Shabbat Table“, Rabbi Chaim Wilschanski is quoting the famous Rabbi Avraham Twerski:
“Every day is a challenge and one only has to worry about how to elevate his lifestyle today. One must be patient and break the challenge into manageable pieces. It provides the means to advance tomorrow. Make each day count ! No one should ever say: The Torah expects too much from me so I will not even start !”