Chronological age is just a number. Would you like to know how old do you act? Most people feel younger or older than they really are – and this subjective age has a big effect on their physical and mental health. Imagine, for a moment, that you had no birth certificate and your age was simply based on the way you feel inside. How old would you say you are? Like your height or shoe size, the number of years that have passed since you first entered the world is an unchangeable fact. But everyday experience suggests that we often don’t experience aging the same way, with many people feeling older or younger than they really are. Take this quiz below to find out what your real age is!