Secondary aging is characterized by nine cellular and molecular hallmarks including genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, Stem Cell (SCs) exhaustion, and altered intercellular communication. Exercise might be a uniquely valid intervention in promoting healthy aging and attenuating aged-related diseases without any side effects. On the molecular mechanism, exercise can effectively arrest all of the nine hallmarks of aging mentioned above. This review describes the mechanisms by which exercise can ameliorate these processes of aging.