The secret of karma yoga which is to perform actions without any fruitive desires is taught by Lord Krishna in the Bhagavad-Gita.
Swami Vivekananda"Blessed are the pure in heart, for they shall see God." Can we see God? Of course not. Can we know God? Of course not. If God can be known, He will be God no longer. Knowledge is limitation. But I and my Father are one: I find the reality in my soul. These ideas are expressed in some religions, and in others only hinted. In some they were expatriated. Christ's teachings are now very little understood in this country. If you will excuse me, I will say that they have never been very well understood.
Swami Vivekananda