A natural stimulus for the healing process is active exercise - provided the exercises are done in a controlled, careful and prescribed manner.
For more information see Back Exercise and Abdominal Exercise Recommendations.
Too much rest will make your pain worse
While pain makes it hard to exercise enough, lack of exercise can worsen the pain by leading to stiffness, weakness and de-conditioning. In the case of disc-related pain, lack of exercise will deprive the injured disc of the nutrition it needs and this can lead to further degeneration and pain.
Additionally, exercise and activity is needed to help reduce inflammation that naturally occurs in the tissues surrounding an injured disc. This swelling can further irritate nerves that are already affected by the highly inflammatory herniated disc material.
See also Exercise and Fitness Help Your Back.
Stretching, strengthening and aerobic conditioning exercises are all important
It may take weeks or months of stretching, but you will find that the increase in your range of motion can lead to sustained pain relief.Stretching your hamstrings regularly is essential therapy for lower back pain and sciatica. If an episode of low back pain has lasted two weeks or more, a strengthening program helps with long term recovery. Typical progragms may include McKenzie exercises , lumbar stabilization training and/or other prescribed exercises.
See also Exercise and Back Pain.
Most doctors and physical therapists will tell you that their patients who are aerobically conditioned tend to have less back pain and sciatica.Low impact aerobic exercise brings nutrients to injured structures in the back and helps them heal. Walking or biking can be effective forms of low impact exercise, as can working out on an elliptical machine. If you are in severe pain, water therapy is an option that can provide multiple therapeutic and conditioning benefits with less stress.
Get an individualized exercise program
Depending on your specific diagnosis and level of pain, your rehabilitation program will be very different, so it is important to see a spine specialist who is trained to develop an individualized exercise program and instruct you on correct form and technique.
Further reading: Sciatica Exercises for Specific Conditions.