Hello, You are having dizziness and fainting. Your diastolic pressure fell to 45 while jogging. If diastolic pressure falls below 60, it will make you feel uncomfortable. Your diastolic pressure dropped to 45 and hence you started to feel uncomfortable, light headed, tired or dizzy. Low diastolic pressure causes a low coronary artery pressure, and that means your heart is going to lack blood and oxygen, ischemia. Chronic, low-level ischemia may weaken the heart over time and potentially lead to heart failure. Get examined and evaluated for your heart issue, you may have to frequently visit a clinic to monitor for cardiovascular disease or heart failure symptoms. Get treated. In the meantime, lifestyle change can help improve symptoms. Dietary changes in salt intake are helpful. Restrict salty snacks & salt intake. You can see a difference in a day or two. Some medications also cause lowering of the diastolic blood pressure, be careful what medicines you are taking. Another reason is age. Aging causes blood vessels to become a little more stiff, and that tends to raise your systolic pressure and lower your diastolic pressure. The more salt you eat, the less elastic your vessels will be. Restrict salt intake. Stay away from addictions, smoking , drugs, alcohol, etc. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician