It is worthwhile for one to make an effort to achieve happiness. Just as the purpose of a plant is to grow, so it is that the main purpose of every human being is to survive and to grow until death.
There are no accidents, all things have a deep and calculated purpose; sometimes the methods employed by Providence seem strange and incongruous, but we have only to be patient and wait for the result: then we recognize that no others would have answered the purpose, and we are rebuked and humbled.