Scientists say just 30 minutes of exercise a week could transform your health

You may not need hours at the gym to boost your health after all. Researchers say just 30 minutes of high-intensity exercise per week — broken into tiny bursts of effort that leave you out of breath — can dramatically improve cardiovascular fitness, lower the risk of dozens of diseases, and even help protect the brain as we age. The key isn’t how long you exercise, but how hard you push yourself.