In future, nerve cell responsiveness to naturally occurring endogenous opioids can be increased via receptor enrichment in the brain too. In principle, we can modulate their lifelong "overexpression", intermittently heightened (or gently diminished) by whatever kinds of personal and environmental contingencies we judge fit. Both functionally and anatomically, our reward pathways can be made "bigger and better". But intelligent emotional self-mastery will involve re-engineering the mind-brain so we derive the most intense rewards from activities we deem most lastingly worthwhile: i.e. prioritising our higher-order desires over legacy first-order appetites. Natural selection has "encephalised" our emotions to benefit our genes. Rational agents can "re-encephalise" our emotions to benefit us.