Choose a good fitting backpack, limit your load and pack it correctly, and choose wisely what really needs to be in the pack. I
Things to do to limit back pain:
1. If you do not need to carry your backpack, then put it down, and do not carry it for long periods without a rest.
2. Carrying more than 10% of your body weight in a pack can be harmful.
3. Use a pack with wide, padded straps
4. Use a pack with chest and hip straps to keep the pack snug and close to the back.
5. Use a pack with multiple compartments for better load
6. Keep the pack from hanging no more than 4 inches below your waist.
7. Use both shoulder straps and do not sling the pack over
one shoulder. You want an even and balanced load.
8. You might try a pack with small wheels on it when carrying heavy longs for long periods.