The fundamental principle of machine learning is that initially you make assumptions( which are usually wrong) and then as you make mistakes, you learn and the mechanism improves. In some cases it even goes further to say that you must make mistakes of a particular order before your tool is ready.
How easy life would be if we accepted this simple truth...in life we can learn a lot from mistakes....(and until we do we may even make the same mistake again and again!)
Thus mistakes are not to be shunned but their causes must be removed without any sense of sadness of excessive guilt about them. Because that's how life progresses.
People and situations are not always what they seem by face value.Misjudgement will happen but it's OK if we learn from it.But it is much better to beleive in goodness of human nature.
Sometimes you are appreciated much more than you realise coz your eyes are closed.Open them and see the beautiful world around you.