An actor shows muscular memory when their actions appear effortless and natural. They achieve this by repeating the movement many times in practice and rehearsals.

Speaking loudly to show aggression in a character is an example of gestures.

An outline of a play that includes details about the plot, movement, and gestures is a scenario.

When it comes to sitting, slouching is an okay thing to do most of the time.

A stage business is a large gesture that a character performs.

Upstaging is considered rude and you should never do it.

When a director tells you to "cheat out" you should turn your face, shoulders, and/or whole body more towards the audience.

We develop character movement and stage business around the character's intentions and motivations.

When creating a scenario, it is important to establish all characters' feeling/desires. This is call "intent" and it is what helps create conflict and tension in a scene, allowing for a resolution at the end.