The present invention discloses mechanisms in the aging process and describes agents to be used for improving mitochondrial function, maintaining the cell cycle- arrested state in senescent and post mitotic cells, and thus preventing or treating age- related diseases or disorders associated with accelerated mitochondrial function loss, telomere dysfunction, and/or deterioration of the growth-arrested state. The present invention also discloses a number of compounds or compositions. The present invention further provides the use of low doses of rapamycin or its analogs as a mimic of caloric restriction in preventing age-related diseases or disorders.