Here is something you don't see every day; an older man acting like a kid. People age differently, with some going completely grey before they are 30 and others turning much later. Its not just appearance, either. Some are old before their "time" and others, well, they never seem to grow old. Consider the following Bible passage from 2nd Corinthians.
2 Cor 4:13-18
13 But having the same spirit of faith, according to that which is written, "I believed, and therefore I spoke." We also believe, and therefore also we speak;
14 knowing that he who raised the Lord Jesus will raise us also with Jesus, and will present us with you.
15 For all things are for your sakes, that the grace, being multiplied through the many, may cause the thanksgiving to abound to the glory of God.
16 Therefore we don't faint, but though our outward man is decaying, yet our inward man is renewed day by day.
17 For our light affliction, which is for the moment, works for us more and more exceedingly an eternal weight of glory;
18 while we don't look at the things which are seen, but at the things which are not seen. For the things which are seen are temporal, but the things which are not seen are eternal. WEB
Attitude makes all the difference in the world. It is the outward expression of an inward state; the glowing of the soul in the real world. A heart on the sleeve with an open invitation to share. Face it, we all grow old sometime (if given the opportunity), but we don't have to grow old in spirit. This is especially true if we look beyond this temporary state to that of the eternal. The knowledge of God transcends this physical world and changes one into something better; something timeless. God has a way of lightening the load, of changing one's attitude and making our life better. And behaving like a youngster doesn't hurt either.