Why do these New Year’s resolutions always mean restrictions?

When each new year rolls around it brings a slew of resolutions -- almost always destined to fail and almost always designed to be a lifestyle subtraction. Taking off pounds or giving up drinking probably head most of these vows for the coming year -- but whatever the resolution, why a negative, why is something being taken away? 

Why not promise to be kinder, pay it forward, do something good for somebody else, if not daily, weekly? Why not a positive, which these resolutions never seem to be.

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