When you're confronted with dangerous or stressful situations, involuntary processes in your body elevate activity in your sympathetic nervous system. In turn, this heightened activity leads to changes such as increases in your blood pressure and heart rate and decreases in food digestion. In modern society, constant triggering of the sympathetic system may play a significant role in the development of various forms of heart disease. If you lead a physically inactive lifestyle, you may increase your base level of sympathetic activity, which in turn may lead to increased heart-related risks