At age 53 the list is getting longer and longer. After having children don't go on any rides that go round-and-round. The need to puke is very overwhelming. (Haven't done it but came really close a few times.)
After 40 & having children don't try the trampoline. Too many things bounce along. The knee drops and sit drops work - but not nearly as easily and you will need to change your panty-liner. (TMI - I know - sorry!) It's also time to hang up the short skirts - evn if you're at the gym all the time and have a great body. It's just too obvious that you're grasping desperately at your youth. It's gone. Say goodbye and gracefully move into your middle years. these are really good years in so many ways.
After 45 stop drinking. Our bodies just don't metabolize the alcohol anymore and it is just not worth the splitting headache the next day. You act like a fool when you've had a few - and an old fool is soooo much worse than a young one. And it's rough on your body and gives you wrinkles.
At 50 it's time to go easy on the roller coasters. I LOVE coasters - but my neck & shoulders do not. Pick out the ones you really, really want to go on and let the kids go on the others. It's also time to get rid of your warm clothes. Hot flashes come when least expected. Wear layers - no matter where you're going so you can take your clothes off, then put them back on, only to take them off again. When your "power surge" makes you so hot that being in your underwear is the only possible relief you need an in-between level of attire - especially in a business meeting. Jackets, sweaters, sleeveless shells underneath, cotton... Consider sleeping in the nude - those night sweats are a killer. Realize it may bring on unintended other consequences - use birth control if it does!
Finally - use make-up judiciously. Look at yourself in broad day light. Heavey make-up on a tan 25 yr old can be over-looked. But as you get up there, there's nothing more scary than a wrinkled, overly made-up lady in a leather miniskirt turn around and look at you.
Youth really is wasted on the young. Can you imagine if you could combine the wisdom and confidence of age with the looks, health, flexibility and energy of youth?! How I wish I had known then what I know now. Clearly God knew what he was doing. Our wisdom makes up for our loss of speed, dexterilty and skill. ;o)