Unguided sitting needs one decision a guided sitting makes for you: where to put attention. The word for the answer is an anchor. A steady thing you rest on, notice you have left, and return to.
Almost anything steady can serve. What follows is the small set people actually use.
The breath
The default nearly everywhere, for practical reasons. It is always present, it moves, and it needs no equipment.
People rest on it in different places, and the place matters more than it sounds. The sensation at the nostrils is fine-grained and takes some steadiness to stay with. The movement of the chest or belly is broader and easier to find. Some instructions follow the whole length of an in-breath and an out-breath; others pick one small spot and stay there.
One thing to be explicit about, because it is a common misreading. This is watching the breath, not changing it. Sitting with the breath as an anchor involves no breathing technique: no counts of four, no holding, no deepening. The breath is observed while it does whatever it was going to do. Deliberate breathing exercises are a separate activity with their own instructions and their own teachers.
A common wrinkle: watching the breath often changes it a little, at least at first. Most instructions say to leave that alone too.
Counting
Some traditions count, some pointedly do not.
Where it is used, the usual form is counting each out-breath up to ten and starting again, or counting up and back down. Breath counting (susokukan) is a common entry point across several Zen lineages, though Dōgen's own instructions for Soto practice point straight at objectless sitting with no counting in them at all. The count gives the mind a small task, and some people find that keeps it from wandering off quite so freely.
The objection, from traditions that avoid it, is that a count is something to do, and doing is what the sitting was meant to be a break from. Both positions are old and neither has won.
If you try it, the moment you notice you are at twenty-seven is not a failure. That is the noticing arriving, exactly as it does without the count.
The body
A single point: the hands resting on each other, the feet on the floor, the weight where you are sitting. A small, dull, reliable sensation. That is the appeal.
Or the body scan: attention moved slowly through the body, region by region, noticing what is there without setting out to change it. This is the practice most often taught with a voice, partly because the sequence is long and easy to lose track of, and it is common in secular mindfulness courses. Done alone, people keep a simple route and accept that they will lose their place sometimes.
Sound
Sound works as an anchor and is underrated, in two quite different ways.
One is resting on whatever sound is there. Traffic, a fridge, birds, the room itself. Sounds arrive and pass and you follow none of them anywhere. Some people find this much easier than the breath, particularly if attention on the body is uncomfortable.
The other is a steady background sound you have chosen. That is the one most people mean, and it is worth a section of its own.
Silence, or something underneath it
There is a quiet assumption that silence is the real version and background sound is the training wheels. Put it down. The people who sit in silence and the people who sit with rain are doing the same thing.
Silence is not neutral
The first thing most people discover in a genuinely quiet room is that it is not quiet. A fridge, a boiler, a car three streets away, somebody upstairs. Closer in, a pulse and a swallow and the sound of your own breathing.
Silence does not remove sound. It removes the sound you had chosen and promotes everything else. For some people that is the appeal: the room becomes something to sit with. For others, an unpredictable environment turns every unexpected noise into a small event, and twenty minutes becomes twenty minutes of small events.
Which one you get depends mostly on where you live.
What a chosen sound is doing
People want different things from it.
Masking. A continuous sound raises the floor so the door downstairs stops being an event. This is the main practical reason people use one, and why broadband sounds work better for it than melodic ones.
Giving the ear something. Somewhere for the part of attention that goes looking for stimulation.
Marking the space. A sound that starts when you sit and stops when you finish makes the sitting a distinct place. For some people that does most of the settling before anything else happens.
Which sound
Rain and room tones have no melody or rhythm to follow, and most people stop hearing them. Drones sit closer to the front: a pitch is something some people rest on and others find themselves listening to. Forests and shorelines contain events, and birdsong invites attention to follow it. Bowls are lovely for four minutes and demanding over twenty.
The general finding people report is unflattering to the catalogue. The sounds that work best for sitting are the least interesting ones.
Headphones or the room
Headphones make the sound enveloping and cut the environment out, which is why people reach for them on trains and in shared houses. The trade is that the sitting happens inside a device instead of in a room, and some people find that closes things in. A speaker leaves the room's own noises audible alongside. Neither is more authentic.
Whichever it is, most people settle on a quieter volume than they started with. Twenty minutes recalibrates the ear.
Switching
You do not owe an anchor loyalty. Many people use the breath for years. Many change with the day, taking sound when the body is agitated, or the hands when the breath feels too close.
Some people never start with the breath at all, and have good reason not to. Attention on breathing can bring a self-consciousness that makes it effortful, or an urge to control it that will not let go. Attention on the body is not always welcome either, for reasons nobody needs to explain to an app. Sound and the hands are the usual alternatives, and neither is a compromise.
A note on effort
Whatever the anchor, the instruction almost everywhere is that this is resting attention, not fixing it. A hand on a rail, not a grip.
What people describe noticing, when effort has crept in, is physical. A tightening around the eyes. A held jaw. A sense of leaning forward at the breath. The standard suggestion at that point is to loosen instead of trying harder.
Hard to convey in writing. Most people find the difference by overshooting first.
