As the title says, sometimes things just happen. It's the normality of our human condition that we are not comfortable with change when something different strikes us initially. One of the most difficult things in this life is to accept change. Sometimes its good, sometimes its bad. The fact of the matter is no matter what, things will always change. One thing is for certain, that we can never be certain about what happens tomorrow.
Every day something new happens, the old problems wither away and new ones come. But hey its not all so bad, as with death there is life. Just as new problems arise, more opportunities come, more treasures are revealed and many fortunes come our way.
The purpose of problems in our existence is to learn from our past failures, never to dwell on them. We all make mistakes. Some worse than others but hey "shit happens". To think "I'm the dumbest person in the World" or "no one else would've done that!" is a mistake in itself. The truth of the matter is we're human! It's part of the learning experience. If you had a choice between a person who never made a mistake in his/her life and a person who made a barrage of mistakes in their time who would you pick? My answer? The latter. Why? Because he hath made mistakes doth learn from them. As the age old saying goes "you can't teach experience" comes into play. Some of the wisest people we know made many mistakes in their lives. It was their ability to learn from them that separated them from the rest of the pack.
The point here is not "never make a mistake", the point here is "make mistakes, its all right, but most importantly learn from them".