Macro partitioning

Daily protein supplementation (12g additional protein via skimmed milk/soy isolate) combined with simple calisthenic and aerobic exercise for 8 weeks significantly increases lean mass and appendicular muscle mass in healthy sedentary adults.

If you are sedentary and want to build muscle, you don't need a gym membership or expensive gear. Add 12g of protein daily (e.g., via a supplement or food) and perform simple bodyweight exercises (like squats and push-ups) 3 times a week, plus walk 150 minutes a week. Doing this for 8 weeks will likely increase your lean muscle mass.