The Reverend Robert Schuller once wrote some prose that capture the feeling I have as get older:

"Spring is past,

Summer is gone,

Winter is here,

and my song that I was meant to sing is still unsung.

I have spent my days stringing and unstringing my instrument"

The other poem, whose author is unknown to me, describes the same regret at not having already accomplished the many things I intended to do, but haven’t yet done:

Just Do it

In youth, because I could not be a singer, I did not even try to write a song; I set no little trees along the roadside, because I knew their growth would take so long. But now from the wisdom that the years have brought me, I know that it may be a blessed thing to plant a tree for someone else to water, Or make a song for someone else to sing"