Consider the mind to be like an ox, and the body to be like a cart being pulled by the ox. The mind provides the intention, but the body actually does the work. In our spiritual practice, the mind provides the intention for enlightenment, and the body performs the sitting meditation. So when the cart is not moving, do you beat the ox or do you beat the cart?

"Beating the ox" means, in terms of the mind, providing some sort of goal, aim, or aspiration to motivate oneself to practice harder. This is how we inspire ourselves to succeed at our assigned tasks in the ordinary world, but when it comes to spiritual practice, expectations of a reward create their own sets of problems. "Beating the ox" might work in terms if the mundane world, but it defeats its own purpose in the realm of spiritual practice.

Zen Master Dogen would instead beat the cart. He once said:

When staying at Tendo Monastery in China, while the old master Nyojo was abbot there, we sat zazen until about eleven o’clock at night and got up at about half-past two to sit zazen. The abbot sat with the assembly in the sodo, never taking even one night off.

While sitting, many monks fell asleep. The abbot walked around hitting them with his fist or his slipper, scolding them and encouraging them to wake up. If they continued to sleep, he went to the shodo, rang the bell, and called his attendants to light the candles. On the spur of the moment he would say such things as; “What is the use of sleeping? Why do you gather in a sodo? Why did you become a monk and enter this monastery?”

"Consider the emperor and officials of the government. Who among them leads an easy life? The emperor governs with justice. The ministers serve with loyalty on down to the commoners. Who leads an easy life without laboring? You have avoided these labors and entered a monastery, but now spend your time wastefully. What on earth for? Life-and-death is the Great Matter. Everything is impermanent and changes swiftly. The teaching-schools and the Zen-schools both emphasize this. This evening or tomorrow morning you may become sick or die. Still you have no idea how your death may come or what kind of sickness you may contract. It is utterly foolish to pass the time you are alive meaninglessly sleeping or lying down while you fail to practice the buddha dharma. Since you are like this, the buddha-dharma is dying. When people devotedly practiced zazen, the buddha-dharma flourished throughout the country. As of late, the buddha-dharma is falling into decay because no one promotes zazen.”

I personally saw him encourage the monks in his assembly in this way, and I saw him make them sit zazen.

One time, his immediate attendant said, “The monks in the sodo are tired and sleepy. They may fall ill or lose their aspiration because of the long hours of sitting. Please shorten the time of zazen.”

Angrily the abbot replied, “We must never do that. People without bodhi-mind who temporarily stay in the sodo would sleep even if we sat for only half an hour or less. Practitioners with bodhi-mind who aspire to practice are happier the longer they are able to sit and therefore, practice much harder. When I was young, I visited various teachers in different regions. I was encouraged by an old master among them who said to me, 'In the past I used to hit the monks so hard that I almost broke my fist. But since I am now old and weak I cannot beat them so hard. Consequently no good monks develop. Since few teachers encourage sitting, the buddha-dharma is dying. I’ll beat them even harder!'” (Shobogenzo Zuimonki, 2-25)