I also suffer from back pain. Hot showers are nice in the morning, and microwavable heat packs filled with something like flax seeds are good, too. If you have access to a hot tub or jacuzzi those are good.
For stressing activities I use a Velcro back brace, which are available in places like Wal-mart near the pharmacy.
For exercise I swim, it's easy to work out in water without straining your back.