sniff, sniff
What makes meditation “meditation” is that it involves a disciplined application of attention. The actual way the attention is applied will vary from form to form, and most traditions have a range of practices that use attention in different ways. They can look quite different from each other, but invariably at their core there’s steady attention.
Attention is like the mind’s “light”, the faculty by which reality is revealed. Like light, it can be directed at various targets or allowed to spread diffusely. Like light, it can vary in intensity. The world you perceive will be shaped by the quality of attention shining on it.
When undisciplined, it tends to constantly jump from target to target, and its preferred targets are the mind’s stream of thoughts and chatter. In this mode, it ends up stitching together a fractured picture of reality composed of a collection of objects and overlaid by a haze of mental noise.
Newcomers to Zen meditation are typically given a breath meditation, so the “target” of the attention is the breath. This may involve counting the breaths (as a way of making sure the attention really is engaged with the breath) or may be just bare, unmediated attention to the breath (considerably harder). In any case, the task is to maintain a steady awareness, with the breath in the center of that field of awareness.
Here, you’re using the attention in “beam” mode. Like a spotlight directed at a performer on stage, the attention illuminates the breath brightly, leaving everything else relatively unattended to. You’ll be peripherally aware of other sensations and thoughts coming and going, but the more you lavish attention on the breath, the less assertive they’ll be.
Inevitably, though, the attention will get snagged by a passing thought or emotion and pulled away from the breath (which, let’s face it, isn’t a very engaging target). Here’s the key: as soon as you realize that this has happened, let the thought go and return to the breath. This will happen constantly in the beginning (and the “beginning” can last quite awhile). It can be really frustrating, but console yourself that this isn’t a situation where unbroken attention is “good” and frequent diversions are “bad”. The only thing that matters is your diligence in recognizing the diversions and bringing the attention back to task. The only failure is giving up.
Don’t neglect your posture in all this. Especially, keep the back and head erect, stretched up to your full (if modest) height. Open up the whole front surface of your trunk; make your chest and belly bloom forward; shoulders back, down and relaxed. Keep your eyes slightly open, but oriented downward.
This seems like a big “to do” list, but it all really boils down to this: lose yourself in the breath. Get fully absorbed in it. All the other stuff is just there to make that easier.