As we start getting old, their is always a concern of bad health, sadness of losing our youth and vitality . We try our best to keep looking young and in good shape.
Once we gain knowledge of the SELF which is immortal, changeless, constant, unaffected by Time and Space then , whether one is in teens or middle or old aged he will detach himself with body mind complex.
Infact one will be full of life , full of bliss and ecstasy. In this state their is no Age.