If you are doing administrative work (especially sedentary), personal advice is that it is best to keep walking fast every day. It takes more than half an hour at a time, because people who spend less than half an hour will sweat, but that is only the reduction of their own water, not the reduction of fat. Only by walking for more than half an hour can the effect be achieved. Keep walking, preferably twice a day, especially for those who have no time to exercise. As long as they use their commute time, at least they won't gain fat. The most important thing is not to overeat.