My father’s neighbor, Mary, celebrated her 99th birthday last month. She looks at least 20 years younger.

She still lives alone, in her own home. She gave up her high heels a couple of years ago after knee replacement surgery; and stopped driving because of cataracts.

On Christmas Eve, my father sent two of my sisters to Mary’s house to escort her across the street to a small Christmas Eve party he was having. He was worried about her walking in the dark on the icy pavement.  My sisters, who are in their 50s, said they had a hard time keeping up with Mary.

What keeps her “young”? (No, she doesn’t do yoga.) She remains physically active and mentally engaged. She goes to lunch with friends, gardens, plays bridge, has her hair done, bakes cakes for neighbors. She’s interested in people. Those may seem like small things, but they make an enormous difference in the quality of her life.

According to WebMd

• Whether physically healthy or ill, people who feel connected to others are more likely to thrive than those who are socially isolated.
• Challenging your intellect on a daily basis – reading, learning a new musical instrument or language, doing crossword puzzles, playing games of strategy with others – protects or improves memory and mental sharpness. Just like an active body, an active brain continues to develop and thrive, while an inactive brain loses its power over time.