I'm 71. I program several hours every day for my own purposes. I'm a little slower, I make more mistakes, it's more difficult to get a broad grasp of an issue, and I tire after a few hours (no more 18 hour marathons). Still, I feel that I am effective and creative. I'm fortunate that people in my family do tend to age slowly. Others may find this harder.
My current software project may be my last. I plan to spend more time writing and socializing. These are interest that I have forgone in pursuit of programming. If you plan to continue programming, great! But, I believe it's best to pursue diverse interests in your career and private life.
