The sorrows one suffers is the outcome of his deeds. The happiness one enjoys originates from his deeds. From the time when one lies within the mother's womb one begins to enjoy and suffer his pristine deeds.
आत्मना विहितं दुःखमात्मना विहितं सुखम्। गर्भशय्यामुपादाय भुज्यते पौर्वदेहिकम्॥