The mind itself is a potent instrument for change, the only one there is.
All change must take place in the mind first,
for all action is a result of thought and the resultant impulse or motivation.
Happiness is what you are, an aspect of what is true.
To be yourself truly, to be the Self, is to be happy and in a state of peace.
Nothing and no one can disturb that peace or take your happiness away unless you so choose.