That's often the question I immediately get when I teach someone a new exercise. It tells me that the patient's focus may be on "getting it over with" rather than doing it correctly. I would much prefer the latter to the former.
With that concept in mind, I've attached this video to provide an example of how you can use an external cue to help "coach" you to use good form. The exercise is called the birdog, and it's an excellent way to improve posterior chain (back side) strength. But to do it correctly requires good core control and stability.
Keeping the foam roller balanced on your lower back requires control and stability in both the sagittal (front/back) and transverse (rotational) planes of movement. It's also hard to race through the repetitions without knocking it off your back. The roller is a simple external "coach" to get your to focus on your form rather than getting to the last rep.
The next time you're doing an exercise, slow it down and focus on your technique before worrying about how many repetitions you will execute. You'll likely find that the slower, more deliberate movements are even more taxing than the high-speed, sloppy method because you won't be masking your compensations with speed. Give it a try.
