Once we have come to terms with our difficult past through gratefulness and have learnt to love ourselves and others there remains only one last thing to do - smile. I know what you are thinking - this sounds too easy. But it is not. The Buddha has taught that we all have an enlightened nature, which means that we are virtually "made of"  happiness and love. While gratefulness and love help us to link in with the love aspect of our true nature, smiling helps us to tune into its joy aspect. Try it out - it is easier than you think. With every smile a small sense of joy is activated in our mind and when we focus on this joy it will grow and expand on its own accord.