The mind is the source of happiness and unhappiness by what it chooses to compare the experience with. If it chooses to compare it to something worse then it will create happiness, gratitude and pride but if it chooses to compare it to something better then it will create unhappiness, bitterness and envy.
The judgment: You are now before Yama, King of the Dead. In vain will you try to...deny or conceal the evil deeds you have done. ... the mirror in which Yama seems to read your past is your own memory, and also his judgment is your own. It is you yourself who pronounce your own judgment.
The method of trying to conquer hatred through hatred never succeeds in overcoming hatred. But, the method of overcoming hatred through non-hatred is eternally effective. That is why that method is described as eternal wisdom.
How easy it is to see your brother's faults, How hard it is to face your own. You winnow his in the wind like chaff, But yours you hide, Like a cheat covering up an unlucky throw. Dwelling on your brother's faults Multiplies your own. You are far from the end of your journey. The way is not in the sky. The way is in the heart. See how you love.
I do not perceive even one other thing, O monks, that when undeveloped and uncultivated entails such great suffering as the mind. The mind when undeveloped and uncultivated entails great suffering.
Peace comes from within. Do not seek it without. It can be argued that peace and happiness comes from the subjective internalised perspective of realizing things could be worse and being grateful they aren't. The alternative view that peace and happiness comes from the objective external perspective of having more and better things than at present, while important for growth, can be a never-ending source of jealousy, dissatisfaction and disappointment. A balance of the two, where people are grateful for what they have while striving for more seems the best blended perspective.
He that distributeth not That which he hath received-- His food, his drink, his sustenance-- Unto devotee, brahman, beggar, wayfarer-- Such a low man as he, they say, is like Unto a lack of rain.
When a monk is an arahant, with his fermentations ended - one who has reached fulfillment, done the task, laid down the burden, attained the true goal, totally destroyed the fetter of becoming, and is released through right gnosis - the thought doesn't occur to him that 'There is someone better than me,' or 'There is someone equal to me,' or 'There is someone worse than me.'
Find out for yourself what is truth, what is real. Discover that there are virtuous things and there are non-virtuous things. Once you have discovered for yourself give up the bad and embrace the good.