When you first start an exercise program, your muscles may retain water to help them heal. This can show on the scale as a temporary gain, no loss or small than usual loss. It will go away as your muscles get used to the new exercise. Don't let a gain on the scale (temporary) stop you from exercise. Exercise burns calories, helps you lose fat so you go down in sizes quicker, makes you look better without clothes, keeps your heart healthy, and builds muscle (which in turn burns more calories). Google "why the scale lies" for insight in to water weight fluctuations.