The One Thing We Give Hashem
Tzedakah & chesed
The Apta Rav teaches that everything really comes from Hashem. Even our ability to learn Torah or give tzedakah is a gift from Him, as the pasuk says, "Everything is from You, and from Your hand we have given to You." Therefore, the main avodas Hashem is to focus on the one thing we can give Hashem that is truly ours alone, which is yiras Shomayim (fear of Heaven). When we accept Hashem's yoke with mesiras nefesh and yiras Shomayim, we create a vessel that can receive and safeguard all the other good middos.
Source: Ohev Yisroel, Emor