The young should not pity the old, but envy them.
Although the young person has endless possibilities ahead of them, the old has endless achievements BEHIND them. Etched into time and history for eternity.
If the older person has not wasted their life, and has applied themselves with absolute vigor, they can grow old in peace knowing that those younger than them will never etch into time the achievements that they have already made permanent and can not be taken back.
Those younger than me will one day be my age.
But they will have never achieved what I have achieved at this moment in time.
I have already won.