I find it too uncomfortable to practice the body scan lying down.

The body scan exercise can be practised lying down, most people find the experience of lying down meditation deeply relaxing, however, if you find the experience of lying down is too uncomfortable, try practicing in a sitting posture or adapt the exercise in other ways to find the most comfortable and easy position for you. When you practice the body scan exercise lying down on the floor use a mat or mattress and a light blanket for comfort and warmth. If your mind wanders off and you lose your focus of attention, which will happen, gently bring your attention back to the particular part of the body you have chosen to focus on. You can also use your breath as an anchor for your mind this brings your focus of attention back to the sensation of breathing in the present moment, and not your busy thoughts.