We therefore have to know His instructions and His desires. Krishna says that in all activities we should depend upon Him. If we are rising in the morning, cleaning our bodies, accepting prasadam, going to work, going to distribute books, worshipping the deities, etc., we have to depend on Krishna. This is the science that we must practice internally. We will otherwise see devotional service as something external.
LFD Vol 3,Being Successful in our Endeavors, Pg 230, 2nd paragraph