Year after year we make resolutions to exercise regularly, eat well, and give up smoking and other bad habits. Following such basic rules can cut heart disease risk by 80 percent, diabetes risk by 90 percent and cancer risk by 50 percent, according to the Harvard Nurses' Health Study. But most of us fail to keep our promises to ourselves. Last year, The Globe asked three prominent local experts for some practical ways to get -- and stay -- healthy. To us, the advice holds up for 2009, but you be the judge. At the end, tell us which tip you think is the most useful.