You cannot learn physics passively. When doing the problems, you will do yourself a favor by working actively, at top speed. It is too easy to say that you will devote 5 hours some evening to physics and go at it slowly and comfortably. Much better to devote 1-2 hours to very active thinking, taking a break and then devoting another hour or so. This course should stretch your mind, and that requires active thought.
Students usually find it best to sit up straight in a chair and work at a desk.
Lying on the floor usually leads to lazy thinking. There is good evidence that students often learn more by working together in small groups where they actively discuss problems. This is true only if each student has first worked alone and done the very best on each problem. It is true only if each student takes an active role in the discussion. This truth will emerge in the exam grades.