The famous Stanford marshmallow experiment was less about subsuming our self-destructive urges and more about trust. What was perceived as an irrational outcome -- eating the marshmallow before the 15 minutes were up -- had its roots very much in rational decision making, albeit influenced by our environment.
Psychological scientists are very interested in the dynamics of future planning, in part because people are so bad at it. There is circumstantial evidence that people who are financially irresponsible also take poor care of themselves. Is it possible that a single underlying trait is shaping behaviors that promote both health and wealth?