Act as a certified personal trainer with 10+ years of experience in bodyweight fitness. Provide a detailed, step-by-step guide on how to train for a push-up, tailored for [BEGINNERS/INTERMEDIATES/ADVANCED] individuals. Include [MODIFICATIONS] for those with [WRIST/ELBOW INJURIES] and [PROGRESSION TECHNIQUES] to build strength over time. Explain the proper form, common mistakes to avoid, and how to track progress. Use clear, motivational language to keep the user engaged and committed to their fitness journey.