It's a new year and as we painstakingly add our health and fitness goals to our list of new year's resolutions, we shudder at the thought of failing to follow through on this one goal yet again. One in three resolution-makers hopes to achieve a health-related goal, whether it is to exercise more, eat healthier, or lose weight. These are all great goals, all worth following through to the end of the year; so why do most people quit on health and fitness-related goals by mid-February?...