Interesting subject, Arnold. I am 70, fully retired but not fully away from my trade. I was a union carpenter for thirty years and since my retirement, fourteen years ago, I have been busy as ever. When I was working, train time was usually Friday nights, well into the early hours of Saturday. Now I find train time is whenever I can get a few free moments.
I must agree that a non-productive day zaps my enthusiasm at times and I spend more time sitting in front of this screen looking for inspiration from others. But when my creative juices are flowing, I can get immersed in a project so deep, that when SWMBO calls my name, I startle.
My favorite quote is, "I'm in my own little world. But it's okay, they know me here".