6 months ago I herniated a disc in my lumber while training for the PST. I have worked with doctors and physical therapists specializing in sports medicine and spinal injuries to recover. They have had me doing primarily arching exercises. My physical therapist has encouraged me to start swimming again, starting with just 20 minutes a day and increasing gradually. If swimming doesn’t bother it I will add light calisthenics after one week. After a month I will try running. I have also changed my nutrition, drinking at least a gallon of water a day, taking NSAIDs, and the upper limits of vitamin C, vitamin D, glucosamine, and magnesium. My question to you is how to best safely prepare for the PST and BUD/s while injured, then how to best safeguard against injury during training.