I think most of us think that they already had negative experience in their life, which taught them a good lesson. But I dare assure you that it's not so! Even if we had such experience, at times we cannot get a useful lesson from it, coz it's difficult to fairly analyze a situation which happened with us personally, we overuse our emotions and have only personal attitude towards the situation. That's why my idea is that we should learn by mistakes of our friends, memories of some popular people and even movie stars… Try to analyze the story of some person's success or, on the contrary, failure. You may write down on paper what the person did wrong and what would you do if being in his/her shoes… Be sincere in your answers and soon you will be much wiser and be able not to repeat some widespread mistakes, even without having negative experience of your own life…