"sravanam kirtanam dhyanam." Dhyanam means to engage your mind in meditation for thinking about and remembering the glories of the name, form, attributes and pastimes of Sri Krishna. So now you have engaged your ears (sravanam), you have engaged your tongue (kirtanam) and you have engaged your mind (dhyanam). All the sense organs should be engaged in the service of Sri Krishna. He is the only master of all the senses. So He is called Hrshikesha. Hrishik means sense organs and isa means the enjoyer of those sense organs. If there should be any sense organ not engaged in His service, then the world might enter through that loophole. You should prevent worldly views from entering into the heart to spoil one's consciousness of Sri Krishna.