I'm in my 50's and I feel smarter than I did in my 20's. I'm less energetic certainly, but I can focus better now. And I feel like my knowledge and understand

I'm in my 50's and I feel smarter than I did in my 20's. I'm less energetic certainly, but I can focus better now. And I feel like my knowledge and understanding of mathematics, politics, economics, sciences, history, people, etc, is much better.