As psychotherapist Annette Nuñez, Ph.D., LMFT, tells mbg, she equates mental age with things like executive function, emotional development, and overall maturity. These things, she says, usually come to us with time as we get older, but for some people, they may feel, act, or think in ways that indicate a younger mental age. According to clinical psychologist Carla Marie Manly, Ph.D., what we consider maturity “is generally defined as the ability to wisely and appropriately manage developmental responsibilities in mental, emotional, behavioral, and social arenas,” as well as other forms of maturity like physical maturity, developmental stage maturity, and career maturity. Since then, much of the research has stayed in the realm of studying children with developmental disorders. But as interest in longevity grows, so, too, does research into the aging brain. “While there’s no test you can take at home to definitively say how ‘old’ or ‘young’ your brain is, we can think of a young and healthy brain as being at peak function,” brain researcher Marc Milstein, Ph.D., writes in his book The Age-Proof Brain. He notes that factors like balance and coordination, sharp memory, and the ability to get through the day effectively are all tied to how “old” your brain is. And as Milstein explained on a recent episode of the mindbodygreen podcast, your brain can actually appear older than your actual age, too. Nevertheless, it can be fun and entertaining to take a quiz for self-discovery purposes and even to help you identify areas for growth if your mental age isn’t what you’d like it to be. But on the off chance that you’re unhappy with your quiz results, here’s what she recommends. There are also plenty of books and online resources about emotional intelligence (EQ), maturity, and personal growth, such as our guide to improving EQ. But Nuñez also emphasizes the importance of self-acceptance and reframing limiting beliefs about yourself. If you’re 35 and feel like you’re 18, how can you look at it as something beneficial and unique to you? In general, minding your health (especially brain health) is sure to make you feel younger. There are brain exercises you can do as you age to keep the mind sharp, for example. Milstein also recommends brain-healthy habits like walking with friends (which research2 says can help ward off dementia, BTW), getting enough exercise, eating a nutritious diet, and getting adequate rest. Additionally, whether our mental age is young or old, we should always strive to keep learning for the sake of our brains and personal development. As Milstein writes in his book, “Think of your brain like a bank account; the more deposits we make, the less our net worth is affected by withdrawals. We make deposits (new connections) by learning new things; as we age and naturally lose some of those connections, there are simply more remaining.” Ultimately, though, an older mental age often translates to wisdom, and Nuñez notes there can be benefits to your mature mindset. “No matter what age you are, it’s so important to keep a healthy mindset and reframe any negative thinking around what makes you, you,” she tells mbg.