"Love work; despise public office; and do not be intimate with the ruling authorities." (Avot 1:10)

From the teachings of our Sages, and from tradition as explained in Chassidic texts, it is clear that work is important in itself (and not only as a means to an end). Not only does work use up a person's time so that he does not remain idle, thus avoiding sin, but, in addition, when work is done for the sake of Heaven, a person fulfills the Divine mission which has been imposed upon him - to purify and elevate the physical world.
[See Ohr HaTorah, Yitro p. 951 (3)]

The 39 categories of work done during the week rectify and elevate the earth's natural power…

The 39 categories of work done during the week (plowing, sowing, etc.) rectify and elevate the earth's natural power to grow things for man to eat, upon which he lives.

A person who recites a blessing over his food, both before eating it and after, imbues the food with holiness. And even afterwards, the energy and strength which the food gives him, by which he prays, learns Torah, and fulfills mitzvot, is elevated and is merged into the words he recites in the Shema prayer, "…G‑d is one…and you shall love..."

The same rule applies to all the other categories of work which produce food, clothing and shelter for man.
[Rabbi Shneur Zalman, Likutei Torah Vayikra 20d (3)]

The "primeval snake" (i.e. absolute evil) marred all of Creation, and brought 39 curses upon the world. Therefore, a sinner - upon who rests the spirit of impurity derived from the "poison of the snake" is given 39 lashes.

Similarly, regarding the 39 categories of work which are forbidden on Shabbat - one who transgresses, earns those 39 curses, and one who guards against even inadvertent transgression will be blessed. This is also true during the week - when a person does the 39 categories of work (during the week) for the sake of Heaven, he draws down the aspect of "renewing in His goodness, constantly, every day, the work of Creation", and this rectifies the 39 curses. Regarding this spiritual type of work, our Sages state, "love work".
[Tzemach Tzedek, Ohr HaTorah, Yitro p. 954 (3)]