To enjoy good health, your brain must communicate well with your body. To achieve that, it's important to maintain spinal strength, flexibility, and balance.
Two exercises that are great to reach those goals are Yoga and Swimming. Both are rhythmic and symmetrical, encourage chest expansion and deep breathing, and implement several spinal ranges of motion.
I know it's hard get to a pool with busy schedules and probably even harder to find a heated pool in cold weather, but especially if you have disc problems or other degenerative issues that would benefit from non-weight-bearing exercise, the effort would be worth it.
Yoga can be done at home or in a studio/gym setting. Some of my favorite Yoga DVDs are from Yoga Zone. They have several to choose from and even have some for back pain and other issues. Usually there are two 20 minute sessions on each DVD, which is easy for even the busiest people to fit into their schedule.