Also known as "mental rehearsal," imagery is a skill that researchers have studied extensively in sport psych settings, and which has repeatedly been shown to enhance performance and make sports and exercise more enjoyable (Weinberg, 1981 and 2008).
When you mentally rehearse, you create or recreate an experience in your mind. This could be an optimal performance from a real memory, or an ideal performance you've created with your imagination.
Using sounds, sights, sensations, and even smells, you draw on your senses to experience success and to practice execution of a skill in your mind. You can use imagery before a workout or just before a specific lift or movement. If you compete, you can mentally rehearse on rest days, during warm-ups on practice days, and pre-performance during competition days.
Working on one of "the big 3" lifts? Or your pull-up? Visualize yourself executing it perfectly just before you practice. Let's take the deadlift as an example.
See yourself approaching the bar... planting your feet... getting your air... getting your hands on the bar and pulling the slack out... driving your heels down... pushing off the floor... finishing with the hips... Bam!
Visualizing your lift can build confidence, prime your thoughts and expectations for success, and increase the practice (or "reps") you get with the exercise.