Walking is a great workout that most people can do. There are many ways you can improve your walk and get more out of it every time you hit the pavement.
Start your day off with your normal walk but instead of walking as you normally do try power walking. Swing your arms in an exaggerated manner as you briskly move your legs. The difference between power walking and jogging is that with power walking one foot is always on the ground. Try to power walk daily.
Do climbing or rolling hill walking exercises on the treadmill. This will provide a difficult workout that changes in pace, strength and skill. Basically it is meant to mimic climbing a mountain or hill. This type of workout will work your calves, thighs and hips. Make sure that you wear appropriate running shoes and keep your feet flat on the treadmill at all times.
You can also wrap ankle weights around your ankles to maximise your daily walk. You can take it one step further and wrap wrist weights as well. This will increase the difficulty level and force you to work harder with every step. At first it may make your wrists and ankles sore but that is just your body getting used to the extra weight, with time it will become easier. Try walking using the toe ball heel method. As your foot comes down, have your toe meet the ground first and then let your foot slowly glide down to the ball and lastly the heel. This will relieve pressure on your knees and ankles.