Put down two headcovers 10 yards (9 m) apart and use these as the boundaries for your game. Now do the same exercise but try to hit your five balls within the 10 yard (9 m) space.
Every time you miss a shot, increase the space between the headcovers by two paces. Every time you win the game, decrease the space between the headcovers by two paces.
Keep a record of your results. Over time you will see some dramatic improvements.