Nowadays I think they say, and it works for me (degenerative disk disease, 2 back surgeries already) is exercise rather than rest. While you are lying down, do the assigned stretches. Try not to sit is great advice, as is the heat/cold thing. Also, don't overlook the benefits of a good massage - you'll feel better AND it helps with the muscle problems. Just make sure the massage therapist knows what's up before they start...

Bites the big one, back trouble does. My latest episode was a sacro-iliac sprain - I didn't even know you could sprain your ass! Months to recover from that one, especially since I had a sitting job...