Today is National Exercise Day, a day to encourage and celebrate physical activity. The sun is out, temperatures are rising and many of us are embracing the outdoors after being cooped up all winter.

Two new studies suggest the changes we need to make for a healthier, longer life are much smaller than we think.

Spontaneity is freeing, and we could all use more unstructured time in our over-scheduled lives—just maybe not in the gym. When it comes to your health and fitness, if you really want to see results, ...