I have often heard many people said that they would never do/don that and it sounded like they were gonna uphold the promises they made to themselves forever. Yea, maybe they did keep those promises for a month or two, or for a year. They were weakened by some special force that was far more powerful than their own willpower. And thus, they succumbed to that formidable force and became what they initially vowed never to become, or wore what they previously thought was gaudy and inappropriate in their eyes.
Unfortunately, I have to concede that I am one of those people who have let their arrogance to cause their own downfalls. I have learnt that one has to be very cautious about using the right words when intending to make a point or to convey a message across - you wouldn't want the other party to misconstrue your words now do you? Only then people won't misjudge you or have the impression of you as being a liar. As long as we think before we say aloud our thoughts and are aware of the consequences, we should have no qualms about saying "never" to things that are harmful to us. However, don't use "never" frivolously.