My 10-year-old neighbor, Ben, came over to visit Saturday afternoon. "Where have you been the past couple of days? Your dad said you were doing some kind of walk," he asked.

I told Ben that yes, I had taken part in a walk in the Houston area. That morning I had laced up my tennis shoes and, along with my good friend Mara (whose mother has dementia), strolled the 5K route that comprised the Alzheimer's Memory Walk in Sugar Land, Texas.

"So why did you do that?" Ben asked. I told him that by...