When it comes to achieving great things, setting the goal should be the easy bit. You decide what you want, come up with an awesome action plan, and then get to work. In reality, setting goals is deceptively tricky. In fact, much of our success depends on setting the right goal in the right way. Get this part wrong and you're likely to miss the target. These are four of the major mistakes people make when setting their goals that ultimately lead to their failure.