Of course as you age things slow down. The main point is to feel good.
To do that you need to constantly improve your diet and exercise as you age.
In your 20s you do what you like and usually have little or no price to pay.
As you age, the price for lack of exersice and bad diet has a higher and higher toll.
Good news is it happens slowly. I am in my mid forties and feel great, love to have sex and party. Just not as much as before or for as long, but I still love it.
I am very happy!. Don't be afraid of growing old, be afraid of growing old badly.
Che'lu