If the speaker communicates that they are strongly motivated, sincere, and really care - that promotes interest. Strong, purposive gestures and facial expressions will tend to eliminate extraneous body movement and maintain the interest factor. Only actual practice in public speaking can produce one having some control over these aspects. Language can help promote feelings of interest in the audience. Frequently, it helps to use language symbols that stimulate vivid visual pictures in the minds of listeners.
Light can glimmer, gleam, or sparkle.
Movement can flow, flutter, flicker, skip, struggle, or stampede. People can be visualized as jovial, surly, morose, and grumpy. The metaphorical nature of language can work for you and you can help the process along. The points of comparison are usually not literal, but figurative. Technically, on some level of abstraction, anything can be compared with anything else.