5 Tips for Improving Physical Endurance
Endurance exercise is any activity — walking, jogging, swimming, raking — that increases your heart rate and makes breathing harder for an extended period of time. If you are new to working out — or returning after a long absence — be sure to start slowly.

Build up your endurance. Start out with as little as five minutes of endurance activity and then increase the time gradually.
Up the effort. Start out at a lower level of effort and work your way up gradually — especially if you've been inactive for a long time. It may take months to transform a sedentary lifestyle into an active one.
Intensify your workouts. Your goal is to work your way up to moderate-to-vigorous activities that will increase your breathing and heart rate. The exercise should feel somewhat hard to you.
Lengthen your workouts. Your goal is to build up to a minimum of 30 minutes of endurance exercise on most or all days of the week. More often is better, and every day is best.
Divide and conquer. Once you reach your exercise goals, you can divide your routine into a minimum of three ten-minute sessions. Doing less than ten minutes at a time won't give you the desired cardiovascular and respiratory system benefits, and you should be getting a total of at least 30 minutes of activity a day. (The exception to this guideline is when you are just beginning to do endurance activities.)

Source: The National Institutes of Health (NIH). The NIH does not recommend or endorse any company advertised on this site.