Building huge muscle mass is extremely hard work. It takes years of very heavy lifting. Genetically, it's not something that most people can achieve even if they're trying. It's certainly not something that will sneak up on you overnight. The average fitness enthusiast will get good results by incorporating weights into their workout routine 2 or 3 times a week.
Strength training is a very important part of any well-rounded exercise program.
It increases your metabolism, reduces your risk of sports injury, and lowers your risk of Osteoporosis by increasing bone density. This pesky problem is called a side stitch. It's a sharp pain just below the rib cage caused by a cramp in the diaphragm muscle, food in the stomach, or gas in the intestines. An obvious tip for avoiding the ones caused by food is to wait an hour or so after eating to begin your workout. Try bending over while using your hand to push up on the stitch.