Cleanliness is essential for making advancement in spiritual life. There are two kinds of cleanliness: external and internal. External cleanliness means taking a bath, but for internal cleanliness one has to think of Krishna always and chant Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare. This process cleans the accumulated dust of past karma from the mind.
Bhagavad Gita 13.8-12,
If one doesn’t practice remembering Krishna while one is struggling for existence, then it will not be possible for one to remember Krishna at the time of death.
Nothing is impossible for the Supreme Lord, but all His actions are wonderful for us, and thus He is always beyond the range of our conceivable limits.
Srimad Bhagavatam 1.8.16,
We have no freedom not to serve Krishna; we have choice.