Health Issues, Exercise & IPOARM

Hi all - Im recently new to MFP and to the IPOARM life changes and have a few questions about exercising - I decided to wait a bit after getting started on the new eating habits before starting on the gym (I've just been walking and doing light exercises at home so far). Here's my question - I have issues with the discs in my back degenerating - I've actually lost 2 inches of height in the last few years and according to my last MRI - there is mild to moderate degeneration in all of my discs. So my question is - now that Im ready to go to the gym to get going on the strength training and just more working out period - are there any exercises that you guys (& girls) would recommend me NOT doing so I dont aggravate an already aggravated back. I know that just losing the weight will help with my back (Cant wait!!!) but I dont want to make it worse in the short term making it harder for me to reach my long term goals. I will be talking to the trainers at the gym about this too just wanted to see if I could get some ideas before hand.