You might think that the title of this post is in reference to your swing. It's actually not. It's about something you do before you ever begin your swing - stabilize. Before you can make a swing, you must have a solid foundation. How strong is your foundation? Let's find out; try this:
Assume your 5-iron golf stance as you normally do. Now, slowly push your pelvis all the way forward (flexing your lumbar spine). From here, slowly poke your butt all the way out (fully extending your lumbar spine), all the while maintaining your golf posture. Repeat this process about 10 times.
Can you do it without shaking? If so, you have the beginnings of a great foundation for your golf swing (and you are also in the minority). If you do shake while trying to perform this, do this exercise several times a day for the next couple of weeks. You will begin to see that it becomes easier and easrier. The thing you may not see, however, is that strengthening the muscles that control this movement can help prevent injury to your low back when playing golf. This is not the only way to test core strength and this exercise does not target all muscles that need to be strengthened in order to build a strong golf foundation. But it is a simple start that is very much worth your time.