A Somatic Movement practice is often done lying down. This is because it’s easier to notice how we’re moving and address our habits when we’re not in a position (such as sitting or standing) that is familiar to us. We also have a different relationship to gravity when lying down and it’s often easier to let go of tension in this position.
But that doesn’t mean you only do your practice lying down.
Although sometimes it’s useful to not be in a position you’re familiar with to notice what you’re doing, sometimes it’s useful to be in that position. Learning to sit or stand or move comfortably if it’s something you spend a lot of time doing is an important part of a Somatic Movement practice. When you practice Somatic Movements while seated you are more likely to be able to notice your habits and self-correct in the moment.
Finding time and space to lie down on the floor is also not always practical, so having options is good too. Just like something is better than nothing, somewhere is also better than nowhere.