When we look forward to a certain day, we count down the days until that day arrives.  The Sefer HaChinuch famously asks why when it comes to Sefiras Ha’omer and the giving of the Torah, why we count the days that passed instead.

The Chidushei HaRim zt’l answers that each day of Sefiras Ha’omer, we rise to a higher level of purity. Therefore, we aren’t only excited about receiving the Torah on Shavuos, but we’re also happy with each day that passes, because each day brings us closer to our Father in Heaven.