Hi @Fenn sounds very much like myself although I haven't tried to build any upper body muscle yet . Must get off my **** and give it a go instead of just walking !!
I had a PT every Saturday morning, she would make me do upper body but as soon as I went it alone, I stopped all strength training because it was just so hard for me, went full running cardio with some exercises that suited that, I was getting incredible success with weight and blood sugar so went with it. In hindsight I wished I had tried harder at it. I hope you find more motivation than I did