Interior monologue is defined as the thoughts you have running through your brain or the things that you silently tell yourself.(noun)
An example of an interior monologue is when you silently give yourself a pep talk, or when you have thoughts running through your brain about how the presentation will go later that day.
See interior monologue in Webster's New World College Dictionary
See interior monologue in American Heritage Dictionary 4
Learn more about interior monologue