I'm not sure I get what Paul's trying to say here. Why is doing what you want a requirement for action? There's a known neurological difference between the brain's "wanting" and "liking" systems. Is he mixing up the two?
he is probably talking about free will and at some level , we don't really control our desires. free will in that sense is an illusion at some deeper levels of desires.
At some nth level, we don't really control our desires or wants. The information that we receive from the enviornment is shaping our uncouncious leves of wants or desires. In that senese, it is very important to control or filter the information we receive from the environment to some achieveble extent.