There are different approaches to physical culture. Some are excellent, and others are downright harmful. After spending almost 25 years as an avid participant and a teacher in the field of physical training, I think I can offer some valuable insight into what works and how to build serious muscle.
1) You cannot make up for too little effort by doing more exercises.
Effort is the key. That means you have to work hard. I've had the opportunity to work with pretty much every type of athlete over the years. When someone is serious about wanting results, he always shows up for training. He will be in the gym. The problem, more often than not, is that he shirks the really hard stuff. Pushing (really pushing) is not fun. Sometimes it hurts, and it always demands a heck of a lot more than simply spending the time going through the motions.
It's practically universal. Trainee A wants to develop better legs, so what does he do? He follows a leg routine that consists of several exercises. He does four sets of each of those movements and ends up doing between 12 and 20 sets. By the end he is certainly tired. Despite his fatigue, however, he won't have actually done much to develop maximum size and strength in his legs. If, instead, he did two or three brutally hard sets of squats, he would almost certainly achieve his objective. It's grueling but effective.
The same principle applies to virtually everything in bodybuilding. Select one good, basic exercise and work it to the max. Don't delude yourself into believing that five sets of 10 reps with a comfortable amount of resistance will do. It won't. You must, of course, build up to such training gradually and sensibly, but you must build up to it and do it if you want maximal development.
2) Use as much weight as you can while maintaining good form.
I know all about cheating and using short-range movements. Such training does have its place, but only occasionally and for short periods of time. You need to work your muscles through their full range of motion against maximum resistance to make the best all-around progress.
You must also constantly try to increase the amount of weight you handle. As soon as you can perform an exercise correctly with a given poundage, you should add weight to force the developing muscle to work harder. The trick is to add exactly the right amount of weight and not an ounce more. Once the overload on the muscles is unmanageable, effective training ceases.
3) If a workout has been done properly, only rest and nutrition will ensure progress.
The truth is that Nature, as the late Harry B. Pascall once wrote, doesn't enjoy being pushed around. Once your body has had enough, it has had enough. Period.
You may think that you'll make fast gains by spending more time in the gym and doing another three or four exercises. Actually, that could ruin your chances of ever making any gains. Remember, weight training itself does not build muscle. Weight training tears muscle down. It is the rest and nutritional intake following training that causes the body to build up muscle.
You may feel that you could easily do more after a good session. That's exactly how you should feel. If you feel completely wiped out, to the point that you're still exhausted hours or even days later, you have overtrained. I've never encountered any evidence to suggest that anyone requires more than one to two hours for a quality, total-body workout. Stronger men need heavier weights, not more training.
Once you've broken down the muscle fibers, you should rest, eat properly, maintain a tranquil frame of mind and live a well-balanced life. (I'm convinced that someone who lives a healthy, well-balanced life enjoys far better gains from his training than the fanatic who lives for another quarter inch on his chest.)
I'm not doctrinaire about diet. Bob Hoffmaz pointed out that dietary habits differ from nation to nation, yet all nations produce great lifters. It's a matter of discovering what suits you. That doesn't mean you should eat junk food simply because you like it; it means you know what quality foods you enjoy and how you want them prepared.
Some moderate supplementation is a good idea. A vitamin-and-mineral tablet, some extra vitamins C and E and, for the ladies, calcium is a very good idea. Nevertheless, good food is critical.
Adequate rest results from a combination of sleep and sensible relaxation coupled with a calm mental outlook. Powerful, well-built men in peak condition are generally pretty mellow and easy-going. That's not a coincidence.
4) Hereditary potential cannot be altered, regardless of how you train, eat or live.
As an extreme ectomorph, without much potential for strength or development, I know very well that heredity determines how much anyone can develop. Don't waste time, money or effort following advice of some charlatan who tells you that you can, despite the limits of your hereditary potential, develop into a world-class lifter or bodybuilder. You can only develop in accordance with those limits.
If you've got the potential, you can become a champion, and you'll know it within the first year of training. You'll sprout muscles like a monster. Your strength will treble quickly and even treble again. Don't fret or despair if you're not a natural for bodybuilding. Accept what and who you are and develop every ounce of size and strength nature will allow.