| Having reached 40 myself, I've been ruminating on the term "Life begins at 40". I used to think it was a whistling-in-the-dark kind of statement, something said by old people to rationalize the fact that they aren't young anymore. That may be the case, but there is a lot to be said to support it.
If you reach the age of 40, it means that you've managed to avoid a great many pitfalls. It only takes 3 years of a clean record to get an Army Good Conduct Medal, and it rates above the National Defense, Korean Service Medal, Vietnam Serice Medal, Humanitarian Service Medal, NCO Professional Development Ribbon, Overseas Service Ribbon, and many other awards. Even the Army knows it's hard to stay out of trouble.
You've managed to not die in a foolish car crash, haven't gotten knifed or shot in a street brawl or bar fight, killed in combat, burned yourself to death playing with matches, or succumbed to the many other ways younger people manage to kill themselves or get killed by others. You are still at risk for some of these things, but as an older and wiser person, you are at a significantly reduced risk. Check out the insurance rates for middle-aged drivers.
You've probably had your heart broken (maybe more than once) and are wiser in the ways of love. You realize that you can't change a person, and you must love them as they are, just as they must love you as you are.
You are more respected in your position, and usually have earned it, no matter how clueless your kids think you are. You are old enough to know your business, and young enough to still be enthusiastic about it (if you choose to be.)
You have probably reached the point where you are financially able to pursue your dreams of travel and adventure, and if you have taken care of yourself, you are still healthy enough to catch some of them. One of the reasons that middle-aged guy buys a Porsche and takes a road trip is because now he can afford to.
You (hopefully) have a circle of friends with deep roots, people you've known for decades, the kind of friend that would help you bury a body if you asked them to, and would even bring their own shovel. The kind of friend that you can talk to all day, or communicate with by not saying a word. The kind of friend that you may only see a couple of times a year because you live on opposite ends of the country, but is closer to you than your happy-hour drinking mates.
You're old enough to know better, but young enough to still get in trouble. | 
