It is often said that 40 is mid life. But I’d argue 50 is more the middle. We don’t remember much from under 12. Then 12-18 is a wild ride of changes and growing up, though for most people many things are done for them by parents or boarding school. Food is covered and so is lodging.
So adult and independent years start around 20. Then 20 to 50 is 30 years. And 30 more years puts you at 80. That’s a great lifespan for those that make it.
So 50 is the mid point. Stay healthy and fit, both physically and mentally, so you increase your chances of a long and enjoyable life!