rational but behave irrationally?

Is it possible to be rational but behave irrationally?
Well there are two definitions involved in this sentence- one is the definition of the person and the other is the definition of rational. the latter is quite simple although there is a degree to which one might tolerate irrationality without terming a person "irrational" butthe former surprisingly is a bit more complex.
take for example a person addicted to drugs but doing all the right things to stop. Are they irrational drug takers or are they rationally dealing with a drug problem. Well it depends if you take the "addict" part of their brain to be "them". If you take that as obviously being part of them ask yourself what if your irrationality was caused by a disease in your leg or some drugs you got from your doctor or maybe some family members? What if the root of the problem is a decision you made years ago (for example you would have been a better engineer than a doctor but you studied medicine instead of engineering).
Basically the question of 'who am I" is much more complex than many people (esp the links) give it credit.