Jason, you said what I just was going to post! My back does much better if I keep on moving. My worst back pain actually happened when I was working a sitting secretarial job full time in my late 20's. I got out the chair wrong, wrenched my back and was in pain in the bed for a week.
I am in my 60's, a 5'0" little old lady, and just starting my food forest. The biggest thing is that most of my earthwork is best done right now when the ground is moist. It turns to cement during the summer. At least where I hadned wood chipped yet.
I also just started keeping my horses on my own property. I used to board them so someone else was manhandling the bales and feeding my horses. Now I go pick up my own hay. Sure, they load it fine at the feed store, but I have to unload and stack it myself. We are talking 100+ lbs. 3 string Western bales. So I learned to tip them onto a hand truck, tip it over, build up my stack in stages so I can flip the bale over to get it into place. I also don't stack them more than 3 high. I can't use hay hooks because I don't have enough arm and hand strength to pick up a bale that way. I can stack my 16 bales, but anything more than that I lose interest, more than wearing my body out. So learning to use physics in your favor is key.
Weeding by hand, hoeing, pruning, planting etc... I just do it in small chunks at a time. Put up a metal staked wire fence by myself using a post pounder. Made my own redwood planked raise beds. It keeps me moving without stressing my body out. I have had gout attacks where my whole body suffers from pain and lack of movement. Just have to watch and eat cleaner to keep the gout away otherwise it's a downward spiral of losing muscle tone. I am missing an ACL in my left knee, and my right hip is kinda out of whack because of a slight scioliosis in my back. I am lucky enough to have a good accupuncturist that had also studied Asian martial arts and the associated bonesetting (don't tell the chiropractic board). Seeing her once in awhile helps me keep my wheels aligned. Also the more I ride my horses, the less my left knee tricks out and my back feels better because it improves my core strength.
I'm just coming out of a temporary funk where all my adrenals were drained by a major house move, a loss of my cousin and father all in the same week in 2012 after a couple years of stressfull parental care. I lost my favorite horse two years after that and my new horse gave me a case of PTSD so my normal stress relieving trail riding habits went away for awhile. People started to really get on my nerves so I became a hermit for awhile. But time and space heals, and I'm crawling out of that funk.
I am really happy that I finally have my own place where I could live my permie dreams. I got my first dog since childhood, and enjoying time with him, but that meant I had to work on getting my garden fenced off from his marauding behavior! I planted pears, apples, peaches, hazelnuts, currants and a bunch of citrus trees all in gopher cages. This year my goal is a raised bed in a small part of my property that doesn't frost for avocados and building a chicken coop next to it. The avo's will shade the chickens during the summer, and the chickens will warm the avo's during the winter. I was going to plant more bare root trees this year, but opted not to so that I could get caught up on the avocado and chicken coop projects. I was getting bad about buying plants and not putting them in the ground quick enough, so I gotta work more on infrastructure instead.