The people we consider to be selfless and good, are in fact the most selfish people. Being selfish means following your happiness and well-being at all costs. The only difference between them and us is that they know where their well-being and happiness truly lies. 

You can only share what you have. So in order to make other people happy, you need to be happy yourself. This is not a licence to do whatever you want, the other person be damned! When we go a little further into what makes us truly happy, we realise that it's not possible to be happy if the people who live with you or around you are miserable. 

The people who call selfish are actually stupid, for short term pleasure, they give up on happiness! Also you have to consider that if no good deed goes unrewarded, then no bad deed goes unpunished! 

So lets all be selfish! :)