> As any long time lifter can tell you, putting on muscle mass naturally takes a long time. I don't agree with this. It's generally easy and straightforward to

> As any long time lifter can tell you, putting on muscle mass naturally takes a long time. I don't agree with this. It's generally easy and straightforward to put mass fast: do hypertrophy, sleep 8+ hours a day, eat 2g protein per kg of body weight. That's all it takes. You'll see results very quickly, even with subpar training. Learning new motor patterns (especially firing many muscles/full body at once), improving tendon strength, potentially increasing muscle density, improving physical awareness (say, handstand, or anything inverted, or anything with balance, or splits/pancake/perfect shoulder mobility), cardiovascular fitness - all extremely difficult to achieve (compared to just getting muscle mass).