With your knees upon the mat, bring either your left or right heel in close to your cushion, leaving your foot directly upon the mat. Place your other foot on top of its opposite thigh. This gives you a good stable posture.

An even more stable and balanced posture—although one requiring more flexibility—is the full-lotus posture. Begin by placing your first foot on its opposite thigh instead of on the mat. Then place other foot on top its opposite thigh.

As in the half-lotus posture, bring one foot in close to the cushion, but then place the second foot on the mat in front of the first leg rather than on its opposite thigh. Make sure that both knees are supported, and not floating above the mat.

If you choose to meditate on a chair, sit with your feet comfortably close together and flat on the floor. It's important to have your thighs nearly level with the floor—knees slightly lowered. This will maintain the lumbar curve in your spine, giving you good back support and allowing you to breathe properly. Do not lean against the back of the chair; the base of your spine should either not touch the back of the chair or only rest very lightly against it. The upper part of your back should not touch the back of the chair at all.

Most chairs are sloped toward the back; unfortunately, this will cause some slouching and make it impossible for you to assume a posture that allows you to breathe properly. You need a chair that does not throw you toward the back.