You are driving car, running with seventy miles speed.. it is smashed accidently. But you are alive then you have to change your car. Similarly, we can drive this machine called the body for so many years; then it becomes old and we have to change it for another machine. This is the process of birth and death.
Water is very clean. When it rains from the clouds it is very clean, but as soon as it drops on the ground it becomes muddy. So that muddiness has to be cleansed then water will come out again clean. Similarly, our consciousness is clean, but because it is contaminated with the muddy things of the material nature, it is cloudy.
19
One who is sufficiently intelligent should use the human form of body from the very beginning of life, in other words, From the tender age of childhood, to practice the activities of devotional service, giving up all other engagement. The human body is most rarely achieved and although temporary like other bodies, it is meaningful because in human life one can perform devotional service. Even a slight amount of sincere devotional service can give one complete perfection. — Srimad Bhagavatam, 07.06.01