If you believe you will succeed, you will. Right? Not quite. Research has shown that optimism and the confidence it brings will help you reach your goals, but there is no guarantee. In fact, if you believe that success will come easily to you, you are more likely to disappoint. This is because you'll fail to put in the necessary work. You need to think positively but also be realistic about what achievement entails. Knowing that success is hard won forces you to put in the necessary effort. Don't spend too much time visualizing the end result. Instead, envision the steps you will take to get there.
Source: adapted from "Be an Optimist Without Being a Fool" by Heidi Grant Halvorson