“The most exhausting thing in life is being insincere.”

Yeah what a lousy way to live!

I don't know about the 'most' thing but yep, I like it.

It takes more energy to put on an act or prop up a lie than it is to be true. So why do people do it? Truth is very costly when there is so much invested in the lie (whether we know it to be a lie or not). The truth may set us free from the burdens of insincerity, but the shell game is over then, isn't it. Self-deception is the most exhausting of all.

I'm with Mike, I don't know if it's the "most exhausting", but it'll work.

I've crossed paths with people who thrive on being insincere with others. I guess it somehow makes a small mind feel big/more powerful or important because they have put another person down. I would bet that acting in an insincere way to another person would take a lot of energy out of a person who is genuinely sincere. The genuineness of the person would dictate the genuineness of the sincereity, in my opinion.

How would anyone but an insincere one know whether it's exhausting or not? It may exhaust those who have to share space with the insincere but to the faker??

Dick, just look at the last election. How many times was Hitlery seen collapsing or just spacing out? (by way of an extremely terse case in point)

They weary themselves who would stand in deceit, cut into many pieces, becoming odious to all around them.

Sincerity is as true conservatism is - the original, natural, state of Man.

It is with evident effortlessness that some, primarily sociopaths, exemplify a fearsome faculty for being sincerely insincere.

Certain nominally "progressive" politicians come to mind...