When You Appreciate, Then Hashem Gives You What You Need
Why do people get so little milage in so many areas? They are complaining about their lot from Hashem. Because Hashem may have given them a nice life in all different ways, but as soon as something goes wrong (the business goes wrong, the marriage goes wrong, the nachas goes wrong, etc.), it would be worth your time to start thanking for all the goodness of the past.
Imagine if the more you keep davening, the more Hashem views you as a basically ungrateful person. If you went the exact opposite direction, and just "thanked" all day, you'd go much further.
And the power of seeing only the good can bring back the old good, because the Eibishter might be waiting just for this. In the same way we deal with people, we deal with Hashem. When you appreciate, then Hashem gives you what you need. You are a different person.