Here’s the outline of the 30-Day mass building workout plan to gain muscle. Day 1 – Chest, Triceps, and calves Day 2 – Quadriceps and Core Day 3 – Rest Day 4 – Back, Biceps, and Forearms Day 5 – Shoulder, Hamstrings, and Glutes Day 6 – Rest Day 7 – Rest Day 8 – Chest, Triceps, and calves Day 9 – Quadriceps and Core Day 10 – Back, Biceps, and Wrist