I am beginning to feel old now.
I have slowed down a bit in the last couple of years but found that stamina has come in strongly. Not certain that I want to punish myself with the offroad enduros any longer so I took the more gentle route of road riding. Only a couple of years older than you but at 60 I decided that it was time to get out and ride and enjoy the ride. Especially as in my 60th year I found out about Mountains. I enjoy them but the training gets a bit hard sometimes.
So keep training and we need pics of the birthday PIE. Just don't put any candles on it as I have heard about your Forest fires running out of control
Happy birthday