Do you feel as if the future looks bright and the greatest times of your life are still ahead of you? Then you must be 24, because a "survey of retired people found the life changing highlights etched on their brains happened before they reached age of 25." It's all downhill from there, and if you're worried that you wasted your teenage years and the first half of your 20s, too bad: You may as well pick out the least terrible moment from that period now and settle in on it as the good old days, because soon enough your that's how your brain is going to think of it. What's even worse is that your brain will be right: Whatever better it's going to get has already been gotten, and what's left is the slow trudge to the tomb. But at least you've got your memories.