Loneliness is complicated. You can feel lonely when you lack friends and miss companionship, or when you’re surrounded by people — even friends and family. Either way, loneliness can have devastating health effects. It boosts risk for coronary artery disease, …

When I took up running in college, a friend of mine scoffed at the idea. He hated running and was convinced runners were “wearing out” their joints. He liked to say he was saving his knees for his old age. …