A walking meditation is a variation on a standing meditation.
It has the advantage of being easier on your joints.

Standing meditation is a good alternative
to stimulate alertness if you are drowsy at the time.

Walking meditation is a step beyond standing in promoting alertness.

Again, as with all the other postures, keep your spine erect

• firm, but not rigid
• keep your head balance over your shoulders and hips

Walking meditation is not the same things as a mindful walk.
You may walk mindfully on your way to a specific destination.
You may walk mindfully at a pace that provides some physical exercise.
Beware of the temptation to multitask for the sake of efficiency.

There is a different kind of experience
when you walk with your full attention on
the process of each step, or some other meditative focus.
Some find walking meditation a good match for breath meditation
matching your steps with your breath.
Some find walking meditation a good match for a mantra or
for repeating scripture, poetry, or some other set of meaningful words.  

This experience will be altered

• when you walk more rapidly,
• necessitating attention to any obstacle ahead,
• the more level and familiar the path, the faster you can safely walk
• and still maintain focus on your meditation.

and the experience will be altered

• when your attention is
• divided between focus on the process of walking
• and focus on your destination. ​​

​To explore other options follow the links below:
Sitting in the floor for meditation
Sitting on a chair for meditation
Kneeling for meditation
​Standing for meditation
Lying down for meditation
​
So, balance my head above my hips.   
Anything else about the position of my head?
What to do with my hands?