I have already felt the way you do and I'm only 31. I think 90% of that feeling comes from the type of problems your job is asking you to solve. It's definitely tough to keep the interesting work flowing in, and avoid the tedious "hey build yet another crud app!"

My strategy for my career is to try and position myself into a position of enough authority to decide priorities around software engineering, and what my team is working on. Then I can delegate all of the boilerplate to the younger engineers, and spend more time collaborating on much more interesting and difficult problems.