Trainers can stimulate learner motivation by gaining their attention using arousal and variability techniques. Arousal techniques include surprising discoveries, stories, and games. Variability techniques involve varying discussion, presentation methods, and exercises. John Keller's ARCS model of motivation identifies four key elements: gaining attention through novelty and questions; ensuring relevance through real-world examples; building confidence with clear expectations and feedback; and providing satisfaction through application and reinforcement. Stimulating motivation is important as unmotivated learners may be confused and negatively impact evaluations of the trainer.