It's Friday we'll have a bottle of wine and a pizza. It's Sunday let's lie in bed till mid-day. Soon you stop making new friends, loose touch with old ones, and become dependent on one-another. And your social skills shrink, too. How about ageing.
Many people start doing less and less with each passing decade.
They loose their vitality because they loose their interest in living and they carry on, just existing. So there's shrinkage. Because you cannot stand still. People who retire die earlier than people who carry on working because the latter are more stimulated by doing and stretching than by lapsing into Comfort. Begin engaging in activities that take you briefly into Stretch.