A natural stimulus for the healing process is active exercise in a controlled, gradual and progressive manner.
For more information see Back Exercise and Abdominal Exercise Recommendations.
Too much rest worsens pain
Pain often prevents us from getting enough exercise, but lack of exercise can worsen the pain by leading to stiffness, weakness and de-conditioning. In the case of a disc injury, significant inactivity deprives the injured disc of the nutrition it needs and this can lead to further degeneration and pain. Additionally, exercise and activity is needed to maintain the exchange of fluids in spinal structures and reduce swelling 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 important
It may take weeks or months of stretching, but you will find that the increase in motion provided by stretching leads to significant, 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 (such as McKenzie exercises , lumbar stabilization training and/or facilitation exercises) is critical to long-term recovery.
See also Exercise and Back Pain.
Aerobically conditioned patients tend to have less back pain. 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. 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.