the prime of life

the prime of life

One's happiest, most successful time; the period when one has the most energy, vitality, and potential. Often structured as "the prime of (one's) life." My father was in the prime of life when he was diagnosed with cancer. It's many a man and woman who, in old age, looks back on the prime of their lives with bittersweet nostalgia.
See also: life, of, prime

prime of life

The best years of one's life, when one is at the peak of one's powers, as in She was in the prime of life when she began to lose her sight. The related phrase in one's prime can be applied to objects as well as persons. For example, The roses were in their prime when you last saw them. In both idioms prime means "first in quality or character." [Early 1700s] Also see past one's prime.
See also: life, of, prime