We sometimes think of meditation as being this rigid activity that must be performed under such and such circumstances. Seated Zen practice is the ideal, but not the only option. Meditation isn't about sitting there and thinking you're doing something important; it's about detaching from thought and existing as purely as one can in the present moment.
As you can imagine, this can be achieved in many activities. In Zen monasteries, every menial day-to-day activities are attended to as means of meditation. Monks ritually clean the floors, do their dishes, trim the bushes outside and rake the gardens. There are a remarkable amount of meditative activities. Here's a very short list...
1. Do the dishes.
"A monk asked Zhaozhou to teach him. Zhaozhou asked, "Have you eaten your meal?" The monk replied, "Yes, I have." "Then go wash your bowl", said Zhaozhou. At that moment, the monk was enlightened."Living in a basic utilitarian apartment without space for a fancy dishwasher, my roommates and I share the responsibility of dish-washing. I often find myself doing them as a form of meditation. The repetition of an activity like cleaning a bowl or a utensil (which pile up to incredible heights over time, might I add) serves a similar purpose to counting the breath or repeating a mantra. The whole point is just to practice mindfulness.
2. Walk.
Walking is akin to sitting with your eyes closed. That sounds ridiculous, right? Not at all. It's been said that closed eyes are like a 'movie screen for the ego'. When you close your eyes and try to meditate for the first time, thoughts bombard you from every which way.
Walking involves a similar level of constant stimulation. As you walk, your field of view is constantly changing, and you have no choice but to pay attention to it. Meditative walking involves treating the sights you come across as one treats thoughts in meditation. Just let them pass naturally and don't dwell.
3. Clean your desk.
This is another highly productive meditative task. Throw things away. Sort papers. Clean your keyboard. Do some dusting. Before long, you'll find yourself fully immersed in these activities. Your desk will also end up pretty damn clean.
4. Eat.
I've discussed this before here. Fully involve yourself with your food. Stare at it. Smell it. Savor each bite. This is preferably done in private, since you don't want to be the strange person at the restaurant who looks like he's about to make passionate love to his food.
Modern culture teaches us to wolf food down in mass quantities without any appreciation or acknowledgement of what we're eating. Take a minute and meditate on the act of eating. You'll enjoy your food more, eat less compulsively, and find mindful tranquility in the process.
