Your character is afraid of their own shadow. They creep through life trying to never disturb the dust of living, yet life still happens to them.
Write a scene like that with your character.
Then, throw the whole scene into reverse.
Write the same scene with your a brave, fearless personality at play, loving life, embracing anything thrown their way.
Which is the true definition of the character you want in your story? Is it one of these extremes or a compromise between the two.
Use this technique to not only learn more about your character, especially to identify strengths and weakness, but also to mix things up. Sometimes a brave and tough character has moments of fear, when they feel helpless and out of control. What would it take to make them feel that way? Might be an interesting part of your story.
You can find more writing tips, NaNoWriMo prompts, and writing tips for NaNoWriMo on our Writers in the Grove site.