How many people try "Bootcamp" style workouts, many hours of running on the treadmill or other approaches that don't systematically aim to build muscle and in turn quit trying, because they fail to reach their body composition goals?

It doesn't have to be that way.

A good resistance training plan has indicators of success built in, so that early on when you're in "the valley of disappointment as @Rob_NBF calls it, you still have positive proof you're progressing.

Combined with systematic eating, the only way you can really fail is to not be consistent or to not give it real effort.

This is why most fit looking people got that way with resistance training.

Free weights, machines, calisthenics are all valid examples.