One who is ignorant of scientific knowledge of the spirit soul does not look inside the body to find happiness in the soul; instead, he goes outside to search for happiness
Srimad bhagavatam 7.13.29,
Joy can only be experienced when we offer our love to Krishna.
Everyone is hankering for happiness because by nature we are happy : anandamayo 'bhyasat (Vedanta-sutra 1.1.12). As spirit souls we are naturally happy, blissful.
The spirit soul can be happy only in the association of the supreme living being, the Personality of Godhead, and nowhere else.
Srimad Bhagavatam 3.2.11,
One has to learn tolerance in the face of dualities such as happiness and distress, or cold and warmth, and by tolerating such dualities become free from anxieties regarding gain and loss.
Bhagavad Gita 2.45,
To the degree we cultivate the spirit of selfless service, to that degree we’ll actually find bliss in life.