We tend to look at obstacles in a negative way. This is something we might be able work on, slowly learning to treat obstacles as learning experiences and as positive things in general. I mentioned that before, here.
But this post is about the other side--how we look at the good things we have. There are so many things we have and simply take for granted. This is true, for example, for an employer who mistreats an employee because he thinks it doesn't matter (after all, the mistreated employee is getting paid, right?). It's also true for family and friends we take for granted, often not pausing to appreciate the fact that a person has chosen us to spend a lifetime with (or in the case of friends, even just a rare afternoon at the football stadium).
Once we figure this one out, it's possible to look further and learn to appreciate everything around us.
The ideas above, by the way, are much better explained in this post from Dream Manifesto, where author Jack Canfield writes
When you are in a state of appreciation and gratitude, you are in a state of abundance. You are appreciating what you do have instead of focusing on, and complaining about, what you don’t have. Your focus is on what you have received… and you always get more of what you focus on.