If you sit all day at work, have limited time, or are the restless type, you may feel challenged by a sitting meditation practice. But one of the amazing things about meditation is that it can be practiced in many different ways (though oftentimes, people less familiar with the subject think that sitting with your eyes closed "Ohming" is the only way to do it).
Want proof? Yogi Sayadaw U Silananda writes, "At our meditation retreats, yogis practice mindfulness in four different postures. They practice mindfulness when walking, when standing, when sitting, and when lying down. They must sustain mindfulness at all times in whatever position they are in. The primary posture for mindfulness meditation is sitting with legs crossed, but because the human body cannot tolerate this position for many hours without changing, we alternate periods of sitting meditation with periods of walking meditation."
I regularly practice walking meditation, especially on busy days or when I sit most of the day (which is hard for me; my body doesn't like it!). Sometimes I take 15 minutes out to have a short walk outside to practice (much healthier than a smoke break or a trip to coffee shop), and sometimes I incorporate it into my walk from spin class or to work (or both!). Here's how I do it:
Get comfortable: Try to arrange your bags/scarf/hat in a way that gives you a clear field of view, keeps you comfortable, and is as non-restrictive to normal walking as possible. If you can avoid bringing anything with you, that's ideal.
Relax your eyes: You're going to have to watch where you're going, of course, but when I'm doing a walking meditation, whether I'm in the city or on a woodsy path, a dirt road in Vermont or beachside, I always keep my "looking" in check. In the city that means I don't read signs that come into view (I can't be the only one who otherwise reads every piece of written matter that comes in front of me), I don't look at people's faces, and I do set my gaze somewhere in the middle distance, so that I can easily observe what's in front of me, while not "looking" at anything in particular.
Walk and breathe: At a moderate pace (I slow down my normally very-fast pace, but there's no need to walk super-slowly), start taking deep breaths as you walk. I like to count; five breaths in and six or seven breaths out, calmly and slowly. I do this at least five times to get in the zone, and then keep taking deep relaxed breaths for the rest of my time.
Be patient: Just like with any kind of meditation, it's always easy to get distracted. But this is actually great practice. When a person walks in front of you, you focus on a sign, or you have to stop at a crosswalk or pick your way across a stream, focus on just what's happening, move past it, and keep walking and breathing. If you want to focus on something, notice how your legs, knees and feet all work together to keep you locomoting without having to really think about it.
Finish: I like to officially "close" my meditation sessions, whatever kind they are. A walking meditation is my time to be really appreciative for all that allows me to even practice walking meditation in the first place, so I say a mental thanks.