Excerpts from an article on Reincarnation by Pandit Rajmani Tigunait
We are born to become the creator of our own destiny. Because we have the capacity to conceive the idea of past, present, and future, as well as the capacity to see the connection between cause and effect, we have the ability to bring a desirable change in life here and hereafter. Those who use this capacity to their advantage are destined to reincarnate, while those who are careless remain subject to rebirth.
Individuals who reincarnate are able to descend only because they once ascended. They rose above the world of short-lived pleasure and pain. They clearly saw the transient nature of worldly objects and achievements. They realized the value of life and made a sincere effort to free themselves from the bondage of samsara. They cultivated a clear, calm, and tranquil mind, sharpened their intellect, and acquired the power of discernment. They concluded that their body and senses are tools to identify and awaken their inner potentials, and they used these tools vigilantly. Upon seeing the body and senses falling into the grip of old age and disease, and realizing that these tools no longer served any purpose, they willfully and happily left them behind. This is called ascending instead of dying helplessly.
Such extraordinary people thus have the privilege of descending—reincarnating. When they reincarnate, their knowledge and experience return with them. It may remain dormant for a while, but when the time is right, this knowledge and experience awaken, and these extraordinary people resume their journey at the point where they left it.
Source – Article titled Reincarnation and Rebirth in the Yoga International