The Toll of a Hard-Lived Life
Commentators note that while David was about 70, his extreme frailty was unusual. They attribute his condition—bedridden and unable to keep warm—to the cumulative toll of a difficult life. His many wars, family sorrows, and even his own sins (as Matthew Henry notes) exhausted his strength, showing that even a great man of God is not immune to the physical consequences of life's hardships.