Life can be simply classified into internal and external part. Internal life is all about our ideas and thoughts, which in a broader sense decide our personality/outlook. Clear thoughts give a clear perspective and somehow make life simpler, complex thoughts lead to a confused personality. On the other hand, external life is what we carry in the world; in front of friends, relatives, neighbors, etc . This external life is mainly dependent on our words/actions. If we say good words, speak politely and our actions are socially correct, we will be considered as a nice human being. But if this doesn't happen, our words/actions/behavior is different then we are called as rude/shrewd/off spoken/ill-mannered/abusive. One can always watch his thoughts for maintaining his outlook, and good deeds can always fetch you good name in society.
Life is defined by thoughts and perceptions. Training your thoughts can do wonders to a human life. One can remodel the whole network of thoughts and perception to attain a healthy mind and body. Its neither easy nor impossible. Give it a sincere try and see the results.