If a person always thinking about bad things ,listening bad things (Words),and doing bad things then
his mind will be in the same state.Then these mentally destructed thoughts will effect his doing work with out his conscious.Then he will be in the same state of mind for long years and he will never change in his life.
Consequenly if a person always thinking about good things and doing good things and these things will encourage him to do a good and quality things in whole life.