Everyone needs to constantly improve their skills. If you never challenge yourself to push beyond your personal comfort zone, it is guaranteed you will perform at best average in life.
With respect to photography, I have started a year long project named 365 Days of Birds. Via this effort I often give myself photo assignments which force me to experiment and improve. Two recent assignments have been: Frozen Harbor and First Bird of the Day. Here is a photo I took on Day #3 of the project, a Snowy Owl at sunset (low light conditions are difficult). Learn more via my project site at 365DaysOfBirds.Com.