Everything we experience in this life is all due to our good or bad karma . No one is responsible for our happiness or our sorrows we are what we perform. If with our concious mind we accept the fact for lifetime that whatever has to be done has to be done by me till the time I will keep working hard I will achieve whatever I want, the moment I will expect from others my complexities will start growing . If happiness is in giving I have to give , if happiness is in receiving then also I have to give , the moment I expect that I will recieve something our mind starts thinking about the other person and no two people think a like so whatever the other person gives it will never fullfill our expectations. Expecting from others is the biggest pain if we all want to live with a light heart then we all should learn to perform our all activities without zero expectation.