It helps a great deal to have flexibility in the hips so some sort of exercise that increases that as well as strength in the of the lower back muscles. Lemonda1985's routine would do the job using modest weights. The main image to hold in mind is not one of bending but of folding to trigger the correct movement. Of course, the flexibility in the hips has to be there. I do daily stretching and strengthening exercises for this purpose. It should be remembered that life is not a sprint but a marathon so if you are not now very flexible, it make take some time to get there.