CONCORD, N.H. — A little over a year ago, my twin sister and I celebrated our birthday with a hike, and it was so much fun we vowed to spend time outdoors together every month for the following year.

In the early days of pandemic panic, a Facebook friend posted a pic of brightly painted rocks resting in a houseplant — compliments of her grade-school kiddos. I have a stack of canvases collecting ...