As Jake Danger has shown, the problem isn't your life. It's your perspective. If you are down, just consider where you are compared to the majority of humanity. You have food, shelter and OK health? You're already in the top 25%.
Don't worry about what other people have and how they've gotten it. Life isn't fair... fixating on that fact won't change it.
Decide what you want. If you are saying things like house/car/job/money, I suggerst you look deeper. These are just ends to a means. Decide where you want to be in 5 years, in 10 years, and make a plan. You'll be amazed how well you'll do when you focus on what YOU want, not what OTHERS have.