When I was in my 20's no one would take any notice of my great ideas, and I had no money to do anything about them, albeit I still did a lot of 'stuff'.
In my late 30's and 40's I was full on learning/working/creating/earning and my output was [sometimes!] prodigious.
Now I'm just on the other side of that & I'm tired from all the work and have enough money to indulge that tiredness, so my output is less...
Actually I suppose I should admit it's probably also that I have more toys to play with now!