A smart angler will actually practice mending just like they practice casting. So what's a good mend? It is simply moving the entire line from one spot on the water to another, without moving your flies (or strike indicator if you are nymph fishing) at all. You can't do this by flinging the line, or flicking the tip of your rod from waist level. You should realize that fly rods are long for a reason. Use that length to lift and place. Nothing more. Lift the rod, sweep the line, and set it back down. A great mend is all about mechanics, and requires little effort at all.