Act as a professional fitness video scriptwriter with 5+ years of experience creating engaging content for [TARGET AUDIENCE: beginners/intermediate/advanced athletes]. Craft a high-energy 90-second script for a [FITNESS CHALLENGE TYPE: e.g., 30-day squat challenge, HIIT burnout, endurance test] video. Include: 1. A motivational hook highlighting [KEY BENEFIT: e.g., 'torch 500 calories', 'build explosive power'] 2. Clear demonstrations of [NUMBER] critical form cues 3. Progressive difficulty levels (modify for [SPECIFIC LIMITATION: e.g., knee injuries, limited equipment]) 4. A call-to-action driving viewers to [DESIRED ACTION: subscribe/join program/share results] Infuse [TONAL ELEMENT: humor/seriousness/team spirit] throughout. Structure with 15-second intro, 60-second workout breakdown, and 15-second outro. Include on-screen text prompts for [VISUAL ELEMENTS: rep counters/form tips].