Updated November 25, 2014.

The Good Morning exercise gives your hamstrings a workout as well as your lower back and abs.

Here is how to do it. It works best with a barbell rather than dumbbells.

1. Place a barbell of suitable weight on the shoulders. The bar should rest on the trapezius muscles of the upper back in the shoulder area. Start with a light weight until you get familiar with this exercise.
2. Feet should be placed shoulder width apart.

1. Brace the abdominals and remember to breathe normally -- out with exertion and in on recovery.
2. Keeping the back straight, bend at the hips until the hamstring muscles at the rear of the thigh start to limit your movement. Bend a little further to give them a stretch, but not so that you feel pain or discomfort.
3. Maintain a similar sort of straight back as you would when lifting from the floor: don't curl the back over.
4. The legs should be kept straight: do not bend the knees.

How low you can go with this exercise depends on your flexibility across the posterior chain of muscles including the hamstrings, gluteals (butt) and lower back. Don't push this exercise too far beyond your inherent capability.

You can see a video of the exercise at EXRX.

Find out more about weight training fundamentals if you need background information before you try this exercise.