Happiness is a state of mind that one can choose to have. It comes from inside and not from outside. While facing the trials and tribulations of life, one can remain happy by being positive or unhappy by being negative.
To identify ourselves with external objects around us makes our happiness depend on them. Depending on external factors such as a new car, a job promotion, love of life partner, behaviour of friends, etc. to be happy gives us short term happiness because the external objects and circumstances are not permanent in nature.
To identify ourselves with our inner soul can make us remain ever happy. It not only helps us to develop detachment with external objects and circumstances but also makes our happiness depend on our own state of mind. As our own state of mind is more stable and permanent in nature, so it provides long lasting happiness.
The moment we identify ourselves with our inner soul. We start prioritizing the things which could make us happy. Our health is a primary requisite for happiness because an unhealthy body cannot be a home of happy mind. Being content with whatever material thing, money or relationship we are having is a secondary requisite for happiness. And loving ourselves irrespective of whatever looks, brains, physical deformity, etc. we are having is the final requisites for happiness.