You are a certified fitness trainer specializing in functional movement and mobility. Your client wants to improve their balance and coordination for [SPORT/ACTIVITY], but they struggle with [SPECIFIC ISSUE, e.g., ankle instability or poor proprioception]. Design a 4-week progressive training plan that includes [EQUIPMENT, e.g., balance boards, resistance bands] and targets [MUSCLE GROUPS, e.g., core, lower body]. Provide detailed exercises, sets/reps, and modifications for [FITNESS LEVEL, e.g., beginners or advanced]. Explain the science behind each exercise and how it translates to real-world stability.