What is the one drug you would pay almost anything for?

We have drugs available today that can focus your attention and allow you to absorb oxygen without breathing. In the future, we might have drugs to give you perfect visual memory or erase your fear. What would be the one kind of drug that you would pay anything to take?

I'm not talking about science fictional drugs that would make you invisible or allow you to shoot lasers out of your head. I mean drugs that are actually within our grasp, medically — drugs that could enhance your mental and physical abilities, or change your emotional state so that you are more compassionate or fearless or careful. Maybe it would be a form of heroin that is totally non-addictive so you could experience the ultimate high without ever wanting it again.

What is the one drug you wish for the most?