My sister and I, with our four kids each, occasionally think back to our one-child or two-child selves.
"Remember when we each had just one baby, and we thought that was hard?!?"
"Hahaha, remember when we only had two kids each and we thought that was hard?!?!"
But you know what? It was hard. When I think back to when I only had one child, I think about how difficult it was to adjust to life as a mom, how new everything was to me, and how much I worried. It was hard.