If you often receive these comments, here is a review of how to handle different scenarios:
Some find that maintaining a youthful energy and focusing on positive emotions radiates vitality regardless of chronological age. Tips for Maintaining a Youthful Appearance
Looking "young" can be a complicated experience, ranging from a flattering compliment to a source of professional frustration. Your approach to a "review" of this situation will depend on whether you are looking to embrace it or trying to project more maturity. Navigating the "You Look Young" Experience
Many people mean "you look young" as a compliment, though it can feel like "flattering gab". A simple, confident "Thanks, I know!" or "It's the sunscreen" often works best to acknowledge the comment without lingering on it.