its is pyscological process , the chemical imbalance in brains change the mood of person, the best solution is observe the thoughts , there is nothing good mood or bad mood , close your eyes darkeness - open your eyes all is mayajal(in hindi) - dont think of past because it is waste of time - dont think of future (because it is yet to arrive so that also is time waste) be in present so that with no mind so no thoughts so no question of mood because in present you are with no mind only you are aware.