As long as you walk at an intensity or pace that challenges your cardiovascular system, walking can be great cardio exercise. Here's how to make the most of it.

How Earth's atmosphere transformed from oxygen-poor to oxygen-rich over a span of about two billion years has been revealed by an international team of researchers.

Chronic obstructive pulmonary disease, or COPD, is a group of lung diseases with no cure. CNN wellness expert Dr. Leana Wen ...