What is the most recommended treatment for low lumbar pain without drugs?

Physical Therapy. Physical therapy. But the program should be an active program (exercise) rather than passive (massage and heat). It should include mobilization and stabilization. It also should include lumbar strengthening and core strengthening. Your therapist should help you develop a lifetime fitness and exercise program for both your back and for overall conditioning.
Find the cause. The recommended treatment depends on the cause of the low lumbar pain. However, for chronic low back pain, osteopathic manipulation (omm) has been shown in a number of studies to be very useful for treating low back pain without the need for drugs or with fewer drugs being needed. Find your local do who treats low back pain with omm and see what they can do for you.