YOUNG AT HEART!!!!
Regardless of your age, if you start acting too old, you will actually not benefit yourself at all.
Studies have shown that people who act old, feel old, and can actually suffer from problems before their time. Do not be afraid to be youthful, within reason. The next time you see a man in his seventies running a marathon or a woman keeping up in aerobic class, you can see that by refusing to give into age, they are healthier and live much longer lives.