If you have been writing one book for a long time you can feel stuck in the characters, stifled by the setting, and bogged down by the plot.
This is an easy exercise to clear your mind, but it is also a good exercise to try if you are just getting used to a new character.
What you do is place any or all of your characters in a new and very different setting. I suggest the circus because it gives you a lot of options. If that setting does not appeal to you, or your story is already set in a similar place, change it to the jungle, or a submarine.
If you do not have a character in mind already, you can borrow one of your favorite characters from another novel. You could place Sherlock Holmes at that circus, or play around with what Tom Sawyer would do in that situation.
This is a good exercise to try because it stretches your writing muscles and helps you understand your characters better. It is also a lot of fun.