The good news is that I walked 4 miles all at once, and not much pain. I even did a slow cool down walk (1 mile) soon afterward.
The bad news: this course featured some mild uphill (Illinois River to the entrance to Glenn Oak Park) and while my back handled the downhill ok, that, plus the roots pushing up the pavement on the path made the walk more challenging than I was used to; a 12:52 pace wore me out.
I did PT before driving there and some banded walks to fire my glutes up.

Got back home and did my upper body.
pull ups: 8 sets of 5..though I played with belt, without belt, singles vs continuous. I do better when I set up every rep, tighten the glutes and get the knees up just a bit. Then later, 5 complete reps, with a hold and a slow negative.
I think my descent is where my back arches.
Push ups: 3 sets of 30 inclined, 10 deficit.
Bench press: 4 x 154, 3 x 154, 10 x 134 (I was fatigued)
curls: 3 sets of 10.