As a designer, working for others most of the time can be exhausting. Being forced to be creative because you have to (someone has to pay the bills) is a great challenge.
One way to recharge your battery is to work on personal projects. It doesn't matter if it's a small thing like creating an icon or building an entire website - the main thing is to do something. Something you can identify yourself with and you work on with passion. This passion why you've chosen to work as a designer (although the job is very often poorly paid).
Another great thing about personal projects is that you can consider it 100% your own - you can do whatever you want and don't have to compromise.
Sometimes you can even learn something from working for your own: You can teach yourself new techniques or test fresh ideas. If you're willing to share your work with others you can show it to the world (e.g. via Dribbble or Behance) with the intention to get feedback.
And if you think your projects are good enough you can use them in your portfolio for your next job application.
So what's your next personal project? :)