英语一分钟演讲：跑步有害健康？

Let's talk about exercise today. I used to believe in consistent workouts, like running 5 kilometers a day or 100 kilometers a month. As my running ability improved, I aimed for a marathon. I thought increasing speed and distance was beneficial. However, I was shocked recently by a doctor's speech on cardiovascular health. He said intense running may lead to heart calcification. Light exercises like slow running or walking are actually heart-friendlier. It goes to show, our usual beliefs can sometimes be overturned by new perspectives. We should always stay open-minded to accept and learn.