Your body (its motions and actions) : music and lyrics could not occur without your body doing something. What it does, how it does it, how it feels about doing it, and its overall current condition, can have a bearing on the way your music sounds and feels.
Your body appreciates being fed natural and unpolluted food, plus regularly exercised and rested. It also likes plenty of clean water with lots of different minerals, as those minerals provide the necessary electrical conductivity for your nervous system to work properly, and ideally, in an unpolluted oxygen rich environment.
When your body is functioning well you will usually find your composing experience smoother and easier to do.