I think you're still a long way from getting old ;-)) Apart from that, it's a number on your ID card. Some people are already small adults as children and others have retained their inner child into old age. The change that happens to us over the years, regardless of our attitude to life, is a good thing. It is necessary. If nothing changes for me, I'm dead.

All I want is to be happy.

That sounds understandable, but it doesn't quite match my idea. I like to be happy - these are euphoric snapshots. But what is much more important to me is contentment. That's more sustainable and more balanced. I tend to build on that in the long term.