When one performs a commandment and actually senses that "the reward of the commandment is the commandment,” he sees that it is not only by doing one commandment that he earns the merit to do another, but that the reward of the commandment is the commandment itself.
The very delight and spiritual wealth that he experiences through the commandment is his reward in this world.
Not everyone has the fortune to attain such a level.
–Rabbi Adin Steinsaltz
From Learning from the Tanya, Chapter 14, by Rabbi Adin Steinsaltz