You can meditate while seated, walking, standing, or lying down, as well as while doing other things; however, most people meditate while sitting. You may choose to sit in a chair or on a blanket on the floor for sitting meditation. Have you ever seen such stereotyped pictures of hard-bodied meditators on the floor in pretzel-like contortions in ads or elsewhere?
To meditate, you don't have to look like that or sit in that position.
There are several different postures to choose from, and you should find one that suits best for you.
Why, then, do the majority of meditators sit on the floor? The practice of mindfulness is drawn from many cultures where sitting on the floor is a normal part of life. Many daily tasks, such as feeding and sleeping, take place on the floor in these societies. For certain individuals, lying cross-legged on the floor is a relaxed way to maintain a stance for an extended period of time. The cross-legged posture is considered necessary in some schools of meditation for retaining energy and alertness. Since meditation first arrived in the West, some students considered sitting on the floor to be a positive and effective meditation pose, while others did not; the latter might have saved themselves a lot of needless pain by actually sitting in a chair instead. Most Western cultures are “chair” cultures, despite the fact that some of us can benefit from floor sitting—consider America's back pain epidemic.
It is entirely up to you whose stance you will take: Please meditate on the floor if it feels normal, enjoyable, and helpful to you, and your body is relatively pain-free in this position. Otherwise, you are welcome to take a seat. Any people would rather sit down. For meditation, every place is fine, but some can help you remain more alert than others.
(Unless you have an illness, I don't suggest lying flat because it makes people sleepy.) Of course, your pose can change over time, and you can also use different postures on different days.
If you choose to sit on the floor, a tiny circular cushion (called a zafu) is useful; they can be found at several yoga studios or retail shops that offer meditation-related products.
It will provide you just the right amount of boost while still assisting with circulation. If you don't have a meditation pad, you should still use a couch or bed pillow.
Try not to sit directly on top of your cushion but move toward the front so that your rear is higher than your knees and your knees come as close as possible to the floor. Your legs should be stretched wider so they lie on the concrete. Some people like to sit with their feet on top of each other, but this is not something I suggest because the feet may fall asleep. You should even try placing the floor cushion behind your legs to see how it feels.
Taking a Seat in a Chair
Choose a chair that is firm yet relaxed. You don't want to get too relaxed and you don't want to fall asleep. Avoid the big, overstuffed living room chair. It's best to sit at a desk or in a kitchen chair that provides ample support but isn't as comfortable as your La-Z-Boy. Place your feet on the floor to ensure that you are well-supported. Place a towel or pillow under your feet if you can't hit the floor with your feet. This will give you some support. It's better to maintain a reasonably straight, though not too firm or stiff, stance, as seen in Figure 1. It would be beneficial to place a pillow behind your back to protect you and hold your back straight.
Sitting naturally against the chair is perfect if a pillow is uncomfortable, so avoid slouching.
To foster alertness, keep your back as straight as possible in all postures, but don't make it too stiff, too close, too loose, or too comfortable.
You want to feel comfortable and aware. Your hands should sit on your lap, on your knees, or on the chair's sides. Your tongue should rest anywhere it feels most at ease; often people like to do so on the roof of their mouth.
The most important thing is to relax. Meditation becomes even more difficult if you are in discomfort or attempting to maintain an uncomfortable posture.
You will note that it takes some time for your back muscles to adjust to this position. Sitting cross-legged can cause your legs to fall asleep. Don't be surprised if something happens to you; it happens to a lot of people. Your legs will fall asleep less often as the body becomes used to the pose. Some yoga poses that open the hips will help with cross-legged sitting stability and strength.
A Somewhat Modified Lying Down Position
If you have an injury that prevents you from sitting to meditate, I suggest a changed lying down stance with your back on the concrete, legs at a ninety-degree angle, and feet propped up on a chair. The one disadvantage to meditating when lying down is that it is easy to fall asleep, so try to do it at a time of day when you are most awake.
You may also want to read more about Mindfulness Meditation and Healing here.