The key is to start with an attitude of what CAN I do rather than what CAN'T I do. Obviously with a spinal injury, especially one involving the discs because they are so close to your spinal column, you don't take risks and check with your doctor (says she who ignored all the medicos with her own back injury - do as I say, not as I do
I didn't have a slipped disc though, just a ligament/joint issue)
Go to your doc with a list of sports/exercise that you'd be interested in doing, tell your doc you want to exercise to lose weight and want them to tell you what you can do with no problems (probably swimming and walking) and ask them what other exercise will be ok with due care (maybe something like pilates with a qualified instructor, maybe cycling). Show them your list and ask them what you really really shouldn''t do and what things on there they would give the ok to under certain conditions (they might say you can't do a particular type of zumba move for instance, or say you can ride a bike, but no standing up on the pedals). It's probably a good idea to ask for a referral to a sports physio who also specialises in injury rehabilitation.
Start small and gradually increase. Expect some tenderness - everyone gets muscle soreness when they exercise and if you have a dicky part of your body it WILL complain louder. DO NOT push too hard too soon! Sure, you think you're all motivated and being good but you run the risk of further injury.
I injured my back about a year and a half ago on the treadlie (bike). Turned out to be a sacreliac (sp?) joint injury and I spent a year in physio. Still not 100% but I know how to support it and work with it. The doc I went to originally was a complete ass, however I found a physio who, though expensive, got me on the right track again. Both of them more or less told me "you can't do this and you can't do that" and basically only gave me swimming as an option. I told them "bollox, I can do more than that, now give me some instruction on how to work back up to my previous activities" (I am as stubborn as a mule sometimes). I very quickly learned where the line was and had to take it much slower than I wanted to, but I'm back to cycling and running and boxing etc. In fact, I started bootcamp not long after the injury because I had to quit cycling for a while
My injury wasn't in the league yours is if we're talking prolapsed disc, but the point is you need to keep trying and pushing for it. I think many medicos are used to people who don't want to push themselves and won't accept some (mild) discomfort so they don't recommend you do anything that's not 100% pain free. To do that though you need to understand the difference between acute pain (i.e. you've injured yourself or made an injury worse) and chronic pain (for which there is no corresponding damage or new damage and which can't be treated). That's where a good physio comes in - to teach you how to work with and around your injury and know what is too much.
35kg lost. (November 2005 - October 2006)
15kg gained again (as at October 2010).
Back to the drawing board - Let's do this thing!
"You can't change the winds, but you can change the sails"
"Reach out and take control of what lands in your lap"