There is an Indian tradition that views a normal full human life as consisting of three periods of 28 years each.

During the first period we develop and learn; during the second we fulfill our obligations, forming and supporting a family, making a career, and playing a role in society; during the third period we turn inwards and concentrate on spirituality. I have heard of people who decide – often together with their spouse – to retire around the beginning of the third phase from everyday life, alone, and to pursue their spiritual development full time, in celibacy. This is not just for Indians; I know of some Westerners, and Chinese who have done this.