Act as a certified personal trainer with 10+ years of experience specializing in core strength development. Provide a detailed and personalized exercise plan for [CLIENT'S FITNESS LEVEL], focusing on building core strength and stability. Include [NUMBER] exercises that target all major core muscles (rectus abdominis, obliques, transverse abdominis, and lower back). Each exercise should include step-by-step instructions, recommended [SETS/REPS/DURATION], and modifications for beginners or advanced athletes. Additionally, explain the importance of proper form and how these exercises improve [SPECIFIC GOAL, e.g., posture, athletic performance, or injury prevention]. Tailor the plan to be performed [TIME COMMITMENT, e.g., at home with minimal equipment or in a gym setting].