Living Truthfully Under Imaginary Circumstances

"A Practical Handbook for the Actor" discusses the truth of the moment, which describes how an actor should react to a rehearsed scene as if it were the first time it was happening. This means no matter how many times you film your monologue, or practice, you should add improv whenever you can to make it as authentic as possible. (Number 1 Rule of Improv: never say no!) The chemistry of acting, no matter how similar the ingredients are from one another, can still produce a completely different reaction three, four, even seven times around, which keeps acting interesting!

Hope you guys get my idea :)