If you have a significant amount of weight to lose, it may be too discouraging to think about doing it all at once. Rather than focusing on a number, try focusing on making and sustaining healthy lifestyle changes. For example, set a goal to exercise three times a week. And be realistic about how much weight you can lose how quickly. Aim for an attainable weight loss of 1 to 2 pounds (0.5 to 1 kilogram) a week.