I try and push at least one Coding Challenge solution everyday. I think it's an important exercise to wake up your brain, and make sure you are continously learning.
I first try and solve a problem by any means, then I go back and refactor to make it more readable and as optimized.
If you don't practice what you have learned you are at risk of forgetting it. These problems help me keep on top of my own education and really embed new methods into my memory.