Even more than in other sports, in fitness the sportsman is spared overexerting. However, the training must not become ineffective. People can come to the gym tired after a work day and leave relaxed (physically and psychologically) and not more tired. This is extremely useful for people with sedentary jobs, but also for those who make physical effort at work. They could use the training by choosing a type of effort meant to compensate the one involved in their job.
3. Training takes too long. Again, this idea is true if applied to performance, which can only be obtained by working a lot. But also in this case short and very intense training or training for relaxation and recovery are often performed. In fitness, you can get to 20-minute training, working only super-series of fast exercises, which could involve, directly or indirectly, all the muscles. Anyway, regular training shouldn't take longer than an hour and a half. Otherwise, the body will get into the catabolic faze, when the cortisone secretions 'cannibalize' the muscles.
4. Any type of exercise is good for solving your problems. What's true in this refers to some particular cases like excess of adipose tissue. This tissue can be 'melted' by any kind of aerobic exercise (running, cycling, swimming) if this is continued long enough. Even in these cases it was clear that some exercises are more effective than others. There are situations when only a combination of exercises with a certain amount of each, can provide you with the results you expect. More than that, repeating the same exercise all the time can have as a consequence not only losing balance in the antagonist muscles and in the joints involved in training, but also stopping progress or even regressing.