Psychological say A Good heart is always happy but I think a good heart gets hurts very badly too and expect only good things from others ,they think good thing will give you good results but if you want good things in life then you have to pay something for that.
People psychology: find good people and leave bad one... But the truth is people not bad they have some nature is bad... so find good in people and ignore/correct bad in them.... because in this World no one is perfect