From January 2009 Success Magazine:
Tony Robbins indicates that 80% of people forget their resolutions within one week and 98% have failed or forgotten their new year resolutions within six weeks.
1%-2% of people that attain them know why they want it, they put together a plan, then they execute it. They also model other successful people and take daily steps towards those goals. They measure their results versus their goals and keep them visible or engrained in their mind throughout the days/weeks until they accomplish their goals.