Meditating while walking is a great way to relax especially when hiking through a forest or even walking around to the shops. Zone out or listening to the sounds around you or even concentrating on each breath and each step. This is a very simple meditation and you get some exercise as well.

Walking while meditation is great for children because they don't have to sit and be still they are walking and breathing. All they have to do is be quite though some times hard to do with young children with practice it will become a natural practice of meditation though be aware when children zone out watch out for them as they may wander and get lost.

Breathing while walking is about letting your body choose the breathing style that will help you keep oxygenated and healthy. Though breathing through the nose and mouth at the same time like athletes and instrumentalists is great way for getting more oxygen into your blood stream and muscles to improve efficiency. This also helps with your metabolism.

Counting Steps
A great way to take your mind off things is to count your steps, everyone has at least done this once in there lives and is really easy to do. After a while just let your mind wander and allow the mind to filter through all the thoughts that are jamming up your mind.

Zoning Out
Head phones in some ambient music, and a nice sunny day, walking aimless around your home town, if you live near a busy road, don't try this, or follow a path around a park, somewhere that is safe, focus on the inner you, once you get the practice it will be second nature.

This is how I meditate most of the time. Except during winter where I sit with the heater on a cushion with a enough clothes on to be relaxed.