There was once a heroic knight. He was one of the knights whose triumphant deeds are still recounted in the old stories, in all languages, everywhere. His bravery was great, and his sword was feared, but he was tired of hunting for dragons, ogres and monsters in story after story. He decided to abandon that fairytale world, and come and test out his bravery and skill in the real world. However, when he arrived here, he found no terrible creatures, no evil wizards, not even a poor stepmother to wave his sword at. It was very strange. All he saw were worried people, with the same looks on their faces as he had seen on the faces of people he was rescuing from dragons or ogres. It didn't seem like there was anyone to put them in such fear, or to make them live in a state of such anxiety. Everyone hurried here and there, not speaking to anyone, as though something terrible was about to happen. But, at the end of the day, nothing really bad had ever happened. And so it was, day after day. The knight thought that maybe this could turn out to be his most heroic adventure ever, and he decided to totally devote himself to finding the source of this mysterious worry in the real world. He searched, he inquired, he investigated, he sailed, he climbed… but he found nothing. Not willing to give up, he returned to the fairytale world to speak to the wise old man. "Tell me, wise one. what is the great invisible enemy that strikes fear into the hearts of people in the real world? I still haven't found it, but I won't rest until I have defeated whatever it is, and freed everyone. just like I did here, for so many cities."The wise old man was quiet for a long while, then finally said: "You have neither the strength nor courage to win this battle. the enemy does not exist, yet it is powerful, and as numerous as the stars in the sky." "What?!" Protested the knight, "Is that even possible?" "In the real world, because they have no dragons or ogres, they invent their enemies, and they carry them inside. each person there has an enemy made to measure, which lives inside their heart. for some it is called greed, for others envy, for others selfishness, pessimism or desperation. they have sown the seeds of negativity in their souls, and take the fruits with them wherever they go. it is no easy task to uproot all that." "I will do it," Answered the knight, "I will set them free."And so the knight returned to the real world, bringing all his weapons with him. Everyone he met, he would offer to free them from their negative inner life. However, no one paid him the slightest attention, all he found was indifference and looks of surprise. Finally, exhausted and confused, he threw down his weapons and went over to a rock at the side of the road, to rest. On his way there he tripped over his sword, and fell to the ground, knocking his head against a cockerel which had been crowing in the vicinity. A sad looking little man was passing by, and when he saw this he burst out laughing, so much so that he could hardly stay on his feet. The knight was angry, but on looking closely at the man, he could see in his eyes a joyful shine that he had never yet seen in the real world…and so it was, that the knight finally found the solution to the deep sickness of the people in the real world. They only needed a smile, a laugh, a little help to banish their negative feelings, and to finally enjoy life… from that day on, the knight, armed with a big smile, started recruiting an army of liberators: a large and growing group of people able to remind anyone of the joy that is life. And what do you know! The knight won the battle just as impressively as he always had. 
Our greatest obstacle to happiness is our own self, with its fears, vain preoccupations, and negative patterns of thought. 