The condition of your spirit is of utmost importance

Too many in the world today are focused on the look of their outward appearance and trust me that's not a bad thing. It only becomes a problem when little or no attention is paid to what really matters.
Focus more on the state of your spirit rather than on your body. The only reason you cannot and must not sin with your body is because it injures your spirit. Every time that happens, you deform your spirit which is the real you. It's the same thing about speaking negatively about your body or abilities, saying 'I can't'. It deforms the character of your spirit.
You are not a body but a spirit. You've heard that before, but more importantly, understand that your spirit will live forever.