21 Day Health Challenge Dr. Sindhu Koshy, St. John Macomb-Oakland cardiologist, was interviewed live on the FOX2 News Morning Show to help kick off the St. John Providence/FOX2 21 Day Health Challenge. Let's talk to Dr. Sindhu Koshy about the three steps, so it's three easy things and it begins with knowing your numbers. So, doctor what is the most important number for people to learn? "I think the most important number is probably blood pressure. It gives you…