A telling sign that you need to step up your physical activity is having to stop to catch your breath while walking up a flight or two of stairs. Poor cardiorespiratory fitness—aka huffing and puffing after minor physical exertion, like climbing steps—is a classic symptom of being overweight and/or in not-so-great heart health. But, new research demonstrates that just 11 minutes of exercise performed at home can significantly improve your fitness level. The study, which was conducted by researchers in the department of kinesiology at Canada's McMaster University and published in the International Journal of Exercise Science , compared two groups of inactive young adults: a training group that followed a specific exercise program and a control group that didn't exercise at all. The training group worked out three times a week for six weeks—with each session lasting only 11 minutes total. Each session involved bodyweight moves (no equipment necessary!) that were done vigorous