Tzadikim feel the Taanug in Mitzvos:
Every Mitzvah contains an infinite amount of pleasure. In this world, a person who is attached to physicality is unable to feel the Divine pleasure found in a Mitzvah. However, Tzadikim are able to feel this Taanug, each on his level. The more distanced one is from physicality and the closer one is to G-dliness, the more one is able to feel the Taanug in the Mitzvah.
 Or Torah [Maggid] Parshas Shemos 71