Your lungs

While walking may increase the capacity of your heart, it cannot alter the size of your lungs.

However, it can help your body make better use of the oxygen your lungs supply.

The more you exercise, the more efficiently your muscles become in using oxygen so they can complete the job at hand with less and you are less likely to get short of breath.

The results are rapid and remarkable. A walking programme for inactive people in their seventies found a brisk 10-minute walk, three times a week, reversed 22 years of declining lung efficiency in just 22 weeks, making them feel younger and healthier.