Here’s what it means to grow old(er):

From our twenties on, our physical plant deteriorates. At the same time we get wiser, more resourceful and more able to deal with that deterioration. But there will be ages when we deteriorate faster than we smarten up. This seems to be pretty common around age 40. Try to stay calm and reassess when that accelerated physical deterioration happens to you. If you’re under age 35, I'm probably making no sense to you at all. Enjoy your blissful ignorance while you can!