As his father made his way towards Egypt, Yosef saddled his chariot and went to greet him. Rashi comments that Yosef refused to have one of his many servants saddle his chariot, insisting that he do the job himself, so as "l'hizdarez lichvod aviv" - to demonstrate extra zeal for the honor of his father. How exactly are we to understand this "zerizut" that was manifest through Yosef's preparing his own chariot?
Rav Mordechai Gifter explains that zeal in this regard enhances the very performance of the mitzvah of honoring parents. True, on one level, nothing would have seemed any different would Yosef's handymen have prepared the royal chariot. Yosef would have gotten there just as fast. However, the mitzvah of honoring parents is just that - to honor them. By personally involving himself in the preparations rather than delegating, Yosef afforded further honor to his father. His personal exertion expressed his high regard for Yaakov, that he himself found it worthwhile to roll up his sleeves and work on behalf of Yaakov's arrival in Egypt.
This concept, continues Rav Gifter, underlies the halakhic principle, "mitzvah bo yoter mibishlucho." Many mitzvot can be performed through an agent. One example in the Gemara relates to preparations for Shabbat. One can fulfill this mitzvah by hiring workers to complete the necessary preparations. Nevertheless, the halakha states unequivocally that it is far more preferable for one to perform the mitzvah by himself, rather than appoint another to do it for him. The reason, explains Rav Gifter, is the same reason why Yosef personally saddled the viceroy's chariot. Although one can achieve the same result through an agent, he affords greater honor to the beneficiary of his actions by personally involving himself in the required tasks. We perform a far greater level of "kevod Shamayim" - honor of God - by going through the work ourselves in the fulfillment of mitzvot. Many "Ba'alei Mussar" have stressed the need for "zerizut" - zeal and enthusiasm - in our performance of mitzvot. The greater effort, concentration and excitement that accompany our mitzvot, the greater honor we show for God, and the more we demonstrate our willful and enthusiastic subservience to His word.