When the distance behind is greater than ahead.
And we measure that which might have been,
Against the clock of hours left,
And find we face an unkind choice of holding on
To dreams we know will never fly as we had hoped,
Or sweeping them from our view–under carpets–forgotten,
Until the day the house is cleaned,
When remembrances will prick the heart,
Where fragments of forgotten loves,
Have lain dormant for too many seasons,
And now have lost the strength to grow and flourish,
Never to match the youthful vision
That so powered mind and body in days gone by.
http://www.lds.org/ensign/2018/03/i-still-have-something-to-give?lang=eng
The link above is an article about feeling old and useless. I loved the lines from the poem by Leonard Cohen.