Mine is complicated.
"Never Knows Best" is written on a burning cigarette in a scene in the masterpiece anime FLCL.
Smoking is something that most people say you should never do because it's unhealthy, potentially addictive, expensive, a sign of weakness, etc. If you went your whole life without smoking, conventional wisdom says you would have been better off for it. This is a kind of position that a lot of people have that are usually accompanied by other reserved positions such that the individual goes through life living in a mode of low risk and adventure so that they make it safely to death.
But if not for enjoying cigarettes, I would have never set foot in Smokers' Haven. I would have never picked up the pipe. I would have never gotten a part-time job there. I would have never gotten a full-time job there. I would not be involved in a wonderful community - both the hobby and the industry - that I find interesting and exciting every day.
So does NEVER know best? What would I have been doing with my life otherwise? There are so many interesting and exciting things to do with one's life that you can so easily miss out on for the temporal sake of your constitution. It's going to leave you anyway, eventually. Better to burn out than to fade away.
"Never Knows Best" reminds me to explore, to adventure, and to be confident in tackling whatever I am interested in and naysayers and nannies be damned.