Most people rush into an exercise routine knowing very little, if anything about the muscle groups that they are working, the exercises that they are performing, or what goal each individual exercise is intended to produce. Many times people start running, swimming, or lifting weights without first learning to recognize progress when they see it. Sometimes there is benefit that is never seen, so the person stops thinking the activity a failure, or they are doing the activity wrong, and fail to recognize this as the reason for lack of results.
Sometimes this lack of information is not only the cause of failure by dropping out, but is also one of the main reasons for workout related injury. If a person does not understand the mechanics of an exercise technique, the ability to properly assess and avoid injury, increasing the likelihood of getting hurt.
Your spinal region, and anywhere there are connections between body parts are highest at risk for improper use and injury. If stresses that should be applied to muscle mass is instead applied to the joints and back, not only are you likely to hurt yourself, but if you do happen to avoid injury, the energy you spent stressing these areas is wasted instead of establishing progress toward your exercise goals, such as building muscle or losing weight.
Sometimes people simply know how much of a certain exercise is needed before it takes hold and becomes effective. The thing I hate to see the most is a new person to the gym, running from machine to machine, spending a few minutes in a bulls run, just to leave as quickly as they came, never allowing their body to warm up, and not allowing enough energy to be consistently spent on one activity to produce any results whatsoever.
When you decide on a specific form of exercise, whether it be aerobic activity for cardiovascular improvement & weight loss, or a weight training program to increase muscle mass or strength, it is encouraged to speak with someone who also is experienced in the same method. This can be a friend or a gym partner, but if possible, a personal trainer would be the best solution as they would not only be able to tell you of their experiences, but evaluate your own situation and help you create a personal program that helps you to achieve your workout goals.