Every subject we talk about immediately leads to visualization. All events evoke a picture. You must be able to clarify this picture for the listener and for yourself. For example, if you are narrating the experience of a day spent in Paris, you must be there yourself in your fantasy. Otherwise, how can you possibly take someone else (the listener) there?
If you talk about climbing the Eiffel Tower, imagine yourself, and others, climbing it. Smell the rarified air as you ascend to the top. Experience the movements of people coming down the stairs past you as you continue your climb upward. When you reach the top, imagine yourself taking in the panorama of Paris at its most glorious. As you describe your movements about the city, fantasize every experience. You are there.
In contrast to the Paris experience, consider where your fantasy might go while you narrate a fierce, deadly World War II battle. Soldiers fall all around you, wounded and dying. Cannons and rifle fire. Machine guns, Grenades. React to it.
The listener will react to it with you. Live the experience. It’s all about the ability to experience as your own the experiences and feelings of someone else. The best actors in the business fully understand and make use of this ability in every acting challenge they encounter.