Hopefully, positive thinking is just one of many tools you possess to help you reach your goals. But if your entire plan for the future rests solely on imagining an optimal outcome, you may be disappointed. Combine positive thinking with positive action and you'll be more likely to get positive results.
Changing the way you think takes a lot of effort initially, but with practice, you'll notice big changes -- not just in the way you think, but also in the way you feel and behave. You can make peace with the past, look at the present differently, and think about the future in a way that will support your chances of reaching your goals.