Answer
We are taught that our constant prayer should be, “Please engage me in Your devotional service.” This is the most important prayer in Krishna consciousness.
If we are not engaged by Krishna in devotional service, we will inevitably become engaged in the service of illusion, or Maya. In other words, we end up serving our own mind and senses.
Serving Maya means engaging in activities of sense gratification, which never provide real happiness, never bring complete satisfaction, and instead increase material desires and ultimately lead to frustration.
Therefore, such engagement is called serving illusion. Instead, our real duty is to serve Krishna by engaging in devotional service.
Hence, the sincere prayer of a devotee is always: “Please engage me in Your devotional service.”