For understanding Our Lord’s parables and imagery it helps if one has lived in farm lands where they still use the primitive farming methods he describes.
Most primitive farming is done with just a plow and an ox to pull it. However, when the top soil becomes exhausted, and the farmer wants to turn up some of the fresh soil underneath, he might employ a second ox. The farmer then fits a wooden yoke with two arches over the two oxen.
At such times it helps if the farmer has an experienced ox up front on the left.
That old timer, by long experience, would have learned the lesson of not resisting the urging of the farmer. Such an ox, working in harmony with the farmer, finds something like athletic satisfaction in pulling up rich soil.
In Our Lord’s imagery, he compares himself to such a contented old ox, and he asks us fresh young oxen to follow his example in finding joy by not resisting God’s will.