Premanand Maharaj Ji
What should I do when my mind feels dull and won't engage in bhajan?
When tamoguna dulls the mind, keep the name going loudly
Tamoguna brings sleep, laziness and heedlessness, and the mind engages neither in enjoyment nor in bhajan. The three gunas keep cycling, so keep the name going whether or not feeling arises, and sing loudly when the mind will not engage.
If the mind is not engaged in bhajan, fine, we sing Chaturaji's verses loudly for an hour and three quarters. What will the mind do now? It will have to engage by itself.