So, I'm not in horrible shape - however most of my exercise tends to be on a stationary bike. It's an 'easy' workout, especially since I'm not even paying attention to the exercise.
When Connor wanted to use my cross country skis, and I swapped him for his snow boots & the snowshoes, I knew my toes would be squished. Connor's feet are about a 1/2 size smaller than mine. That's okay. I could deal.
I also had to walk and even run a bit to keep up with him (and keep him from skiing into the other athletes - altho he did run into one). I could feel it in my legs a bit while we were out on the snow.
When Connor was getting more tired, and started falling even more, I wound up having him hold the ski poles, and I held the ends and pulled him along. He's still learning to keep his feet straight anyway, and it was good practice. I didn't expect to get sore from that.
On Sunday, I noticed a tightness around my sternum. It almost felt like heartburn. It took me a bit to figure out I had stretched my pectoral muscles further back than normal.