Every actor should always have an inner and an outer obstacle

10. What must I overcome?

Every actor should always have an inner and an outer obstacle. The outer obstacle is the resistance (usually the other character) to obtaining your action. The inner obstacle is your inner conflict, which you must always plant in a scene even though it can change. There must always be a problem you are trying to overcome. If you think of yourself in life, you're never without an inner obstacle. You'll have seen scenes on stage or screen where the inner obstacle has not been properly planted: you get a load of actors just shouting, over-emoting and sometimes just playing the aggression. If the inner obstacle is there, the anger, fear or hate, for example, then you've got something to fight against in the scene. Much more interesting.

Actors may believe that they can do without formal training. But I have worked with untrained actors, who have landed a film or a TV series on the basis of their looks, and seen them struggle to be able to reproduce what they were able to do in the first take. Natural ability will get you so far, but it's the trained actors who know what they're doing and how they're doing it and can produce that emotion take after take.

To fully transform into a character, to be truthfully and emotionally connected needs hard work, technique, good direction. But the audience should see none of this. They should see nothing other than the fully realised three-dimensional character right in the truth of the moment.

• Dee Cannon teaches acting at RADA

https://www.theguardian.com/stage/2009/may/09/character-building-great-actor