Most people want exercise to create a healthy body as a whole in order to participate in life for the long haul. There is a huge difference between exercise that is appropriately challenging and individualized in terms of mechanical, neurological, tissue and immune system progression vs. generalized exercise to "break a sweat" or burn calories. Exercise is engineering and the framework of your body must be respected. Maintaining the health of your joints is the most important thing you can do. Most people don't think about it until they are older and it starts to fall apart. Training is a process, and the ultimate goal is to build a structurally more sound piece of equipment. Personal training is not about being a motivator, but about being an educator and a teacher. A trainer should be brilliant in mechanics: how to build it, how to figure out all the variables of an exercise and how to implement it appropriately for an individual client. Anyone can train someone that can already do everything. However, hardly anyone is completely healthy orthopedically. The reality is that it is all a puzzle and how you put all the pieces together matters. A trainer needs to know how to build exercises knowing all the variables involved and how to implement them for that individual client. Essentially, they must know mechanics.
Exercise is invasive and the forces you put on the body can have major consequences, if not done appropriately. When having surgery, you expect the surgeon to be skilled in using a scalpel. If he is not, then the damage can be irreparable. The same goes for training. People always seem to be looking for magic from exercises-"3 steps to flat Abs," but there are no quick fixes. Exercise is not a program; it is a lifelong process. Every person has an individual structure and "window of opportunity," and a skilled trainer needs to be able to see all the idiosyncrasies. There are skills in observation and knowing how to manipulate all the factors on a given day, on a given rep, and current tolerance levels. When exercise is safe and efficient, you will achieve amazing results without the unreal time commitment that often derails most aspiring fitness endeavors. Your individual road map will be determined by the current state of your body's physiology and any limitations. The ultimate goal is to maintain lifelong muscle and joint health so you can fully participate in life. Strengthening the muscular system is your only chance to keep your metabolism going and have quality of life as you age.