How would one describe an oveid Hashem? The Gemara in Chagiga (9b) answers this question: "Said Bar Hei Hei to Hillel, 'How can we understand the [redundancy of the] pasuk, 'And you will return and discern the difference between a tzaddik and a rasha and one who serves Hashem and one who does not serve Him.' Is a tzaddik not one and the same as he who serves Hashem, and is a rasha not one and the same as he who does not serve Hashem?' Hillel responded, 'Both he who serves Hashem and he who does not serve Hashem [mentioned in the pasuk] refer to completely righteous individuals. Yet, one cannot compare someone who reviews his learning [only] one hundred times to one who reviews his learning one hundred and one times.'"
Rav Wolbe (Alei Shur vol I pg. 63) points out that the Gemara did not give an example of a person who learns one hundred pages as opposed to a person who learns one hundred and one pages. The reason is that Chazal (cited in Rashi to Vayikra 1, 17) tell us regarding quantity "[it makes no difference] whether [one gives or accomplishes] a lot or a little, as long as his heart is directed toward Heaven." Rather, the Gemara defines "one who serves Hashem" with regard to the quality of learning. He, who after reaching the awesome plateau of reviewing his learning one hundred times, decides to review his learning yet one more time, has demonstrated that he strives for even greater level of clarity and profundity in his learning. It is this attempt for greater quality that places him in the category of an "oveid Hashem."
Throughout the generations all Jews, from the greatest to the simplest, have performed the same mitzvos. They all put on tefillin and tzitzis, they all davened and learned, and they all kept Shabbos. In the spiritual arena, what set one apart from another was the quality of their mitzvos: The level of clarity they had in their learning, the amount of kavana they had during their davening, and the sincerity they felt regarding love and fear of Hashem.
Baruch Hashem, we are all full of mitzvos "like a pomegranate is full of seeds." Yet, our avodas Hashem is not defined so much quantitatively as it is qualitatively. For example, although starting a new learning session to study the Yomim Tovim is definitely praiseworthy, it might be even more worthwhile to start a learning session to gain a greater understanding of the Shema and Shemoneh Esrei that we say on a daily basis. Striving for greater clarity is the manifestation of true avodas Hashem!