There is another reason that we don't persevere. Sometimes we face "Heartbreak Hill." In the Boston Marathon, there is a legendary obstacle called Heartbreak Hill. Starting at mile thirteen of the Boston race course, there are a number of hills, climaxing at mile nineteen with Heartbreak Hill. It's the longest, steepest hill in the race. What makes this hill even worse is that world-class runners "hit the wall" around mile eighteen or nineteen. That is, their bodies have depleted the glycogen stored in the muscles. That glycogen has been replaced with lactic acid.

The muscles are screaming for oxygen. And when you hit the wall, you just feel like you're going to die. Heartbreak Hill tests runners to the very core of their determination and their strength.

There are Heartbreak Hills in life. Life is not on a level grade. We have problems. We have bigger problems. And at times we face Heartbreak Hill.