* Not a doctor. Let me know if they self-heal.
I never knew the importance of core exercise until I squished some discs and experienced pinched nerves. Core exercises build up the muscles around the discs and can help prevent them from getting squished. But you have to also find out which activity is squishing them, and stop that too. Exercise alone won't do it.
Pain is the first part of what happens. Pain nerves run along the outside of the spinal column. Motor control nerves run inside the spinal column, so the second part is the pain goes away and your muscles stop working properly. That's the really scary part. Even though the pain can be bad, as long as you feel pain, you're closer to healing than after the pain goes away and you develop a funny walk or can't do pushups anymore.
In all seriousness, my research and speaking with specialists is that bulging or extruding disc do have blood flow and they will eventually reabsorb. Even sequestered discs with no blood flow will reabsorb. The tricky part is dealing with the symptoms while not worsening the issue.
Even after an epidural steroid injection, I've been told it could be months before my very large extrusion is gone. So it is a very slow process. The good news is that some research shows that your body can actually be better at absorbing the larger extrusions.