I think this is a struggle for most people, and I have really only discovered one way to fight it.
With one simple change of perspective, life becomes beautiful, just as it is. Unfortunately, most of the time we realize the things we have to be grateful for after their place in our lives has been threatened. The other day, I realized I was trapped in the cycle of worry. Once one left, another would follow. I realized that no matter how well life may be going, there will almost always be something to stew about.
What am I going to do with my life?
What will my life look like in 5 years?
Will I get married again?
Will I ever have babies?!
Whew, it's exhausting. But when I think about it, I have SO much. I have my health; that's huge. I have my family. I don't know what I would do without them. With those two things intact, everything else just becomes a bonus.
That is how I want to view my life- a bonus.
It's like good old John said, "Gratitude bestows reverence, allowing us to encounter everyday epiphanies, those transcendent moments of awe that change forever how we experience life and the world."