"It will be most helpful if you change your thoughts and emotions about a negative situation as quickly as possible and feel confident that the Law of Attraction will help everything work out for the best." ~Frank Mangano
This is another great quote that focuses on a few things, one of the most important of which is awareness. Awareness that you're having negative thoughts and emotions. Not everyone can eliminate all negative thoughts forever. But everyone really can change them once the realize they are having them. This is awareness. It's a bit helpful if you do a review at the end of every day and then can recognized that you had negative responses to situations. You can then think of ways that you could maybe respond differently in the future. This is a good start.
But, it's even better if you can become aware of your thoughts and emotions as they happen. Again, you may not be able to change them right away (this takes practice especially depending on the severity of the situation) but you can note when they happen. This would be another great start. As you continue to spot them, you'll soon find yourself wanting to change them because you don't like the way you feel when your emotions and thoughts are on the upswing and you're not down in the dumps.
You'll go about finding situations and people that will help lift you back onto the "better feeling" wagon until you can do it yourself with techniques such as "Reach For A Better Feeling Thought" that Esther and Abraham talk about. The primary idea behind that is that you find some thought that's better than the one you're having right now - it does NOT have to be a happy thought, just a better one. You can go from depression to anger even and that's a better feeling thought. Just try to move up on the emotional scale.
For now, just try to be aware when your thoughts are less than those that make you feel good. Practice that for several days (or it may take you weeks but that's ok too). When you're ready to move on, you will. And you will see great results as the Law of Attraction brings you even greater benefits!