I herniated a lumbar disc (twice) a few years ago and had to take it slow as I recovered.

The best advice I can give is to keep some flexibility in your plans. The worst thing I could do would be to sign up for a backpacking trip with inflexible miles and times and over do things trying to keep up with that schedule or the pace of another person.

My current guidelines are that I'll backpack 8 miles or for 4 hours, whichever comes first. That seems to be working. I'm 67.