There are only two types of emotions - One that feels good and the other that feels bad. Wouldnt you like to 'always' choose the emotion that feels good.
There is a theory that states different emotions are different indicators on how you are "allowing" your alignment with the things you desire. In other words, the emotion you are having is the result of a thought or an event which has ocurred. The more you allow yourself to have good thoughts and choices that you desire the better you feel. The opposite is naturally true.
Above is just an example, as different words are often used to mean the same things. So, it may differ from person to person. The main point is to see your position on the emotional scale and make conscious effort to go up the scale and make yourself feel better.
By being in control of how you feel, you will realize what you want and what you don't want. You will know how to be conscious of when you have chosen something that you do not desire. You will also know how to bring yourself back into your original plan/goal after you have been distracted/discouraged.
You will feel relief as doubts slip away. You will able to sense thngs that are about to happen and enjoy seeing things fall into place.
For further reading, check the following books:
Ask and Its Given The Teachings of Abraham The Law of Attraction
by Esther and Jerry Hicks (Jerry has appeared in "The Secret")
Yes Japanese translations are available - if you search on Amazon.