I've spent over a decade looking at the human body in terms of function, form, and how to best optimize our own body and our daily life. Everybody is an athlete in a sense that they need their body to do the job of daily life.
The more I see people move, the more I'm absolutely convinced that this concept of compensation is one of the root concepts that will help you to do two things. First it will help you achieve your fitness goals, and second it will help you minimize injury in the process.
If you're able to minimize compensations you can target the right muscle and that means you will get results. If you can't do a bicep curl without compensating, you are not going to be able to hit the bicep, and therefore not going to be able to get results.
If you lift something that is too heavy for your ability, you're not going to be able to do it properly.
The problem is when we do something that is outside of our ability. If it's outside of our ability, then the only way we can pull it off is to compensate.
For example, the elderly woman who has to lift 40 pounds to put away her groceries might have to compensate. She can't do it correctly, so necessarily she needs to compensate in order to do this because her structure is not strong enough to do the motion correctly.
“No pain no gain” is not the goal. What you're trying to do an exercise is really to stimulate your body to get better, not blast it into oblivion. You want to put yourself in a position of growth, similarly to the way children are growing. You want to stimulate the body not annihilate it.
One final thought about pesky compensations. Don't get addicted to your workout. The workout is just the process. Stimulating the body to grow is the goal. Stimulation of the body without compensation is the ultimate way to achieve your fitness goals and prevent injuries at the same time.
I hope that made sense. Sometimes I'm not quite sure if I'm getting the point across accurately. If you have any specific questions about compensations or any other fitness questions, please email me at firstname.lastname@example.org.