To serve me should be more complicated than to make sacrifices like cutting out spending to give me the rest. You can follow my instructions - not cumming when I tell you not to, ruining, etc. To serve is to feel pain, that pain means you are alive and that you are doing what I said to.

This pain can be something more. You will do what I say, feel the pain I tell you to feel, and in return you will show that you can hurt to serve. That you can do what I tell you to, no matter what.