I have DDD and Fibro/CFS... I can relate to your pain and exercise issues - I'm also 'only' 40 yrs young!
I have recently started walking and using an exercise bike. I've spent hundreds... not make that thousands of dollars on Physical Therapy trying to eleviate my spine pain and basically the Specialist I went to told me that the only thing he could offer me to help with the back pain is to increase my core strength; which is my fatty abdomen area.
Obviously I'm not going to get crazy and start doing crunches, but I am trying to slowly build up my endurance with walking and various other strenthening and stretching exercises that the PT showed me.
There isn't a quick fix, it's going to take time... but once you make the committment to yourself, you will start to see improvements in your health and your pain!
You have to go to a qualified exercise therapist with experience in relieving disk pressure on a nerve. Generally they will only take referrals from an M.D. after evaluating an MRI to avoid litigation by recommending exercises that would cause damage.
These people are pretty good and the exercises really have to be shown in person.
Exercises to improve muscle tone are used because that is what keeps disc separation within normal limits.
Usually intermittant mild axial traction is recommended.