As you get older, the neural pathways in your mind become like different paths in a forest. Those that are used more often become easier to navigate. The tendency then is to walk down the easier, more comfortable paths (for the most part).
It's a self-reinforcing cycle. The more you walk, the more comfortable you are, thus the more you walk.
Knowing this, it seems to me, one of the best things you can do is to challenge the assumptions that underlie your approach to problem-solving. In other words, think about how you think.
The Art of Possibility is a book that does just that. It's a highly-positive, but not pie in the sky, tome that makes you look at yourself and not only think about how you think, but ask yourself how you can realize the inherent richness and wealth of possibility for learning and growth in any given context.
One of the authors, Ben Zander, is the conductor for the Boston Philharmonic Orchestra and he uses many examples from the challenges of that line of work.
At times, I did get a bit lost and I must admit, I haven't implemented every single practice that they recommend. And, it wasn't one of those "can't put it down" books, but for a chapter or two a night, I found it rewarding and stimulating.