The Supreme Lord can be appreciated only by devotional service. Therefore, one should be fully devoted. One should fix his mind fully on Krishna in order to achieve Him.
One should work only for Krishna. It does not matter in what kind of work one engages, but that work should be done only for Krishna. That is the standard of devotional service. The devotee does not desire any achievement other than pleasing the Supreme Personality of Godhead. His life's mission is to please Krishna, and he can sacrifice everything for Krishna's satisfaction, just as Arjuna did in the Battle of Kurukshetra.
The process is very simple: one can devote himself in his occupation and engage at the same time in chanting Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare/ Hare Räma, Hare Räma, Räma Räma, Hare Hare. Such transcendental chanting attracts the devotee to the Personality of Godhead.
Compilations from the teachings of Srila Prabhupada