Question: At what age do you think people are the happiest?
Analysis

You can answer with a specific age or age range when you think people are the happiest. You can also explain your reasoning, such as childhood being carefree, or adulthood bringing independence and achievement.

Synonyms
Try these synonyms instead of repeating the question:
  1. happiest→most joyful; most content; most satisfied
  2. age→stage of life; period; phase