in the flower of youth

In one's youth, viewed as the finest, most vital, or most exemplary part of one's life. A possessive adjective can be used between "of" and "youth." You're still in the flower of your youth—you have plenty of time to figure out what you want to do with your life. After Arthur Henry Hallam died in the flower of youth, his good friend, Alfred, Lord Tennyson, wrote the poem In Memoriam A.H.H. You won't be in the flower of youth forever, my darling. You need to live—really live—now!