The last thing you want to do in front of a camera is to “act.”
“Acting” is phony and lacks truth. To be a good screen actor you must inhabit the role so that you fully experience the character’s feelings and emotions in the scene. In other words, no acting please.
Depending upon the content of the scene this can be draining, both physically and emotionally. But that’s what good acting is all about – putting yourself in the characters shoes, so to speak, and experiencing what they are going through – not “acting” how they feel, but experiencing and living the feelings and emotions from moment to moment during the scene.
By doing this you will notice a dramatic improvement in your performance, for it will now be real and not contrived.