What does "maintain a testimony" really mean?

Developing/gaining/obtaining a "testimony" in the LDS church means developing a tolerance for disconfirming evidence. So, when someone says, "Get a testimony", what they really mean is, "Develop a high tolerance for disconfirming evidence, and never move from that position."

It is the key to an exclusive club. If you have to go as far as faking it, so be it, no one wants to be left out in the cold.

Church leaders believe this and expressly encourage it. I've heard them say many times that if a person gets into the habit of bearing their testimony frequently, they will eventually actually "gain a testimony".For example, Boyd K. Packer stated "A testimony is found in the bearing of it." ("The Candle of the Lord," Ensign, Jan. 1983, pp. 54-55.)Of course this falls entirely within the realm of WTF?! aspects of Mormonthink. It's like telling a witness taking the stand in the court that they should say that the defendant is guilty and was at the scene of the crime, even if the witness hasn't really seen anything that would support that statement--because, if they say it often enough and with enough conviction they will start to believe it.In other words, if you desire to conform and be accepted by the community, you will be willing to lie to yourself repeatedly and by lying to yourself repeatedly, you will eventually start believing your lies.

Spencer W. Kimball: "Do you think that you can go three, and six and nine and twelve months without bearing your testimony and still keep its full value?"Since something that is true does not lose or gain value as a result of someone repeating that they know it's true, Kimball's real meaning can only be that the strength of brainwashing depends on how often a person can be pressured into pretending that they know something to be true--when in fact they don't know.