In each stage of our lives, there is a particular crisis that must be resolved before we can successfully progress to the next stage. We can only be successful in each stage if we were able to resolve the crisis at the previous stage. What if you don't resolve it? Then it will continue to affect your life.
For instance, during childhood we normally experience problems marked by a battle between initiative and guilt. During adolescence, we search for our identity amidst role confusion. Young adulthood, which usually marks the start of getting into long-term relationships, is characterized by intimacy versus isolation. Finally, during old age, the feelings of integrity for a life well-lived collide against those of despair over what could have been. We generally go through these crises and need to deal with them in order to live our life without hang-ups.
But these are only problems that come up in certain age frames. There are other problems that we experience regardless of age, such as the loss of a loved one, a calamity, an act of apathy or intolerance from somebody close, or difficulty at work or school. The point here is that no matter what, we will always encounter problems, from sunrise to sunset.