Balance's Foundations Plan starts by encouraging you to sit upright in a chair with your feet flat on the floor. This is to help you stay alert while you're meditating, so you can get the most out of your practice.
But contrary to popular belief, meditation does not require stillness or any particular posture. The only requirement is choosing a position in which you feel comfortable and supported.
Many people have wonderful meditation experiences while standing, walking, floating in water, dancing, lying down, sitting cross-legged on the floor, or sitting in a chair with back support. In other words, there are as many meditation postures as there are ways to move your body. So do what's best for you.