Prabhupada tells the story of the wedding party that rowed all night only to find in the morning that they were in the same place. This is because they had forgotten to pull in the anchor. If we are too much addicted to sense gratification, despite good instructions we will not be able to progress. To give up material attachments takes work. If we are not willing to do that work, then we are lazy and inert, and Bhaktivinoda Thakura says that those two states lead to inactivity. Enthusiasm is the opposite of inactivity. “When utsaha is generated, laziness and inertia cannot remain.”
Lectures from a disciple Vol 1, Pg 327 2nd paragraph onwards.