I'm only doing cardio but analyze: should I lift weights? Map current exercise vs. muscle-building resistance training. Calculate: if I built muscle, what's the metabolic advantage and body composition improvement? Show me the strength training benefits: muscle increases metabolism, improves shape. Give me the lifting protocol: start with this program, expect these changes. Include: whether I need to lift not just do cardio, what program is best for beginners, and why muscle matters more than scale.