What do I do when I have to breathe deeply while meditating?

Don’t try to go to your limit. Breathe more deeply but not so as to cause distress. Meditation should be gentle, peaceful.
Force, even force in breathing effort, is counter-productive.

Are you extending your diaphragm properly when you do it?

It seems like I can’t breathe deeply enough into my diaphragm. I’m not forcing myself, I just feel the need to breathe deeply and simply can’t. I can hardly explain further, it’s quite difficult. I try to breathe naturally, but for me to complete a natural deep breath it is frequently necessary to open my mouth and raise my shoulders.

It sounds to me like learning to breathe well could be really useful to you… Do you think your tension and deep breathing issues could be related?

When you say that you can’t breathe deeply, what do you mean by that? What happens?

Two suggestions:
1. Breathe deeply, then a little more, and hold it for a second or two. See how that feels.
2. Try it incrementally. Instead of taking the deepest breath you can, take a slightly deeper one, and then a slightly deeper one, and see what happens as you progress.

I want to clarify that everybody knows the phenomenon I’m speaking of and in lack of—the somewhat pleasant sensation of having taken a complete deep breath. Yeah?

That’s all I mean. I breathe all the way in, as much as I can, but I don’t get that feeling. The breath is incomplete.

I think you’re trying to breathe into your lungs and stomach, instead of filing your diaphragm. Put your hands on your belly button and try to fill your belly with air, pushing against your hands.

I definitely do that. I should clarify that I’m pretty well-informed about diaphragmatic breathing—my mother teaches theater—but nobody has thus far been able to help me with this. It’s quite frustrating, especially having already tried everything that you guys have suggested. Have none of you had this problem?

@quarkquarkquark So do you feel like you’re doing it wrong, or that it’s psychological, or your lungs are shaped funny, or what?

I honestly have no idea. I imagine it has something to do with either my posture or the way I’m storing tension, but when I try to breathe deeper it only increases the tension and makes it more difficult to complete a breath.

Have you ever tried to meditate in a different position to see if that would help you find the breath better? My suggestion would be to meditate while either seated in a comfier position, or if you are truly this tense, to lie down.

IMO, I’ve had better luck meditating on a tense day after I’ve done yoga (helps to release some of the tension), then finish in a prone position and begin meditation.

Do you have sinus problems? Allergies?
These could interfere.
Have you tried cleansing your nasal passages with a neti pot?

I don’t understand why it’s important to experience a full diaphragmatic breathing when you’re doing anapanasati if the goal is to develop focus and mindfulness. The task is to attend to the nature of the breath, body, and attention – to just observe – and the last thing you would do is to manipulate your natural breathing.

Then again, I don’t know whose instruction you’re following. Maybe you’re doing something entirely different or for different purposes.

In all, I don’t think you should worry so much about nailing down a perfect breath. Maybe you’ve always breathed shallow but you never noticed. Maybe one day you’ll start paying attention to different breathings throughout the day. Maybe it’ll grow deeper and more comfortable. Maybe you’ll discover a link between shallow breathing and its cause, or maybe not. The important thing is to sharpen your observation. If you pay attention, you’ll make discoveries out of that 40-minute session. For starter, where does your breath begin? Where does it end?

In my experience, some days my breath felt stuck above the collarbone; some days it flowed into my throat; some days I felt it pushing my rib cage. For one, every day is different. The more you sit, the more sensitive you’ll become to your breathing. For another, I don’t believe that the breath is always naturally long and full. It just echoes your state of mind, no? If you’re resisting something, unknowingly you become restless, and the breath would reflect that. But that’s just my own body wisdom. I’m not supposed to frame anything for you. I learned mine the hard way, a lot of surprising emotions, all the while my meditation teacher simply said, “Oh.”

You might find the instruction in this book helpful. Here’s a classic though a little harder to read.

Anxiety might indeed be the issue. Inhalation activates the sympathetic nervous system, which is our anxiety circuitry, while exhalation lights up the parasympathetic system, which is our relaxation mode. Someone who is prone to anxiety can be even more so through the inhalation, especially if you’re already focussing on this as a “problem”. If this is the cause, then a first step would be to let go of the concern about the quality of the inhalation, as @longtresses suggests, and just experience it as it is. Time and patience will do the rest.

I would just add that it might be a posture problem. If you’re not sitting in a way that allows full expansion of your belly, that would definitely do it. If you’re sitting on the floor, use a cushion that’s high enough to get your hips well above the level of your knees. This will allow you to get an inward tuck to your lumbar spine and let your belly hang out in front. Your whole front should curve outward, never collapse inward.

Try lying down on your back and then concentrating on the diaphragmatic breath. Put your hands on your diaphragm and breathe in and out thoughtfully. Think of a small balloon under your hands.

As you inhale (contrary to the “hold your stomach in” reflex) feel your hand rise up as the balloon inflates. There is no need to exaggerate or hyperventilate.

When you exhale, your hands will sink down as the muscles relax.

Once you get the hang of it, you can switch to a sitting posture.