Maybe it's the crowd I run with. But whenever someone talks about "I wish my legs/arms/back were strong" the immediate response is "So do more squats/pull ups/farmers walks." I have to admit, I think like this too. But seriously, I work in a gym and I can only stand to do up to two hours of training a day, usually broken up between early afternoon and evening, before I'm all "enough is enough!!"
Obviously after shoulder surgery, I wasn't using my back all that much. But when I started up again, I did the normal things that didn't put too much stress on them: ring rows, dumbbell rows, floor press, rack walks, etc.
Here is my back, a couple month post surgery, after trying to work in as much back/ arm work as I can:
Not much to write home about.
Then I got cleared to go back to trapeze class. To say that trapeze is upper body centric is an understatement. My lats were sore for two days after my first class back. But the amazing thing is, for a 1.5 hour class, you just don't realize how much work you've put in until suddenly you can't hang onto the bar anymore.
Five trapeze classes later, and actually doing less dumbbell and barbell work during the week:
I didn't even realize the change happened until I looked at the pictures from last class.
So this is a sort of call to arms to think outside the gym. I'm lucky in the San Francisco Bay area that I have so many activity options at my finger tips. But most cities and towns have parks to play at. Physically demanding volunteer opportunities (think Habitat for Humanity). You just need the gusto to step outside your routine. Adult humans are terrible at that.
Stop worrying about being a beginner at something, learning is where the fun is and where change happens.