Jara, the effect of old age, does not harass a devotee. This is because a devotee follows the instructions and the determination of Narada Muni. All devotees are in the disciplic succession stemming from Narada Muni because they worship the Deity according to Narada Muni’s direction, namely the Narada-pancaratra, or the pancaratrika-vidhi. A devotee follows the principles of pancaratrika-vidhi as well as bhagavata-vidhi. Bhagavata-vidhi includes preaching work — sravanam kirtanam visnoh [SB 7.5.23] — the hearing and chanting of the glories of Lord Visnu, the Supreme Personality of Godhead. The pancaratrika-vidhi includes arcanam vandanam dasyam sakhyam atma-nivedanam. Because a devotee rigidly follows the instructions of Narada Muni, he has no fear of old age, disease or death. Apparently a devotee may grow old, but he is not subjected to the symptoms of defeat experienced by a common man in old age. Consequently, old age does not make a devotee fearful of death, as a common man is fearful of death. When jara, or old age, takes shelter of a devotee, Kalakanya diminishes the devotee’s fear. A devotee knows that after death he is going back home, back to Godhead; therefore he has no fear of death. Thus instead of depressing a devotee, advanced age helps him become fearless and thus happy.

Srila Prabhupada, SB 4.27.24, purport