You know you should add exercise to your daily planner, but you just haven't gotten around to it. "Decide when you're going to walk the night before," says Kirschenbaum. "Commitments are easier to stick to when the 'doing' part is some time away." So pull out your walking shoes before bed and make sure a water bottle is in the fridge, and the next morning the "should I or shouldn't I?" debate won't happen.