When looking at risk for cardiovascular disease as well as all-cause mortality, inactivity is a greater risk for both than any other single habit or practice.
The evidence is clear: “when inactive individuals are compared with active individuals, the inactive individuals increase their risk of cardiovascular disease by between 150% and 240%, and individuals who choose to be inactive accept the same increased risk of heart disease as individuals who smoke a pack of cigarettes a day! Unfortunately, 15% of the adult population in the United States still smoke a pack of cigarettes a day, and 60% to 80% are either not adequately active or completely inactive. Thus, inactivity carries the same risk as cigarette smoking a pack of cigarettes per day and is between 4 and 5 times more prevalent! source
So how much exercise do you need? 150 minutes of moderate-intensity aerobic exercise per week, plus 2 days/week of strength training exercise is the general recommendation released by the CDC recently. Always check with your healthcare provider for specific recommendations tailored to your individual needs, and check out the CDC’s general guidelines here.