We are given the answer to this question in Chapter 2 of this great novel. After the initial enthusiasm of having carried out the revolution successfully, the animals at first experience many benefits to running their own farm. Note how Orwell describes that first harvest:

All through the summer the work of the farm went like clockwork. The animals were happy as they had never conceived it possible to be. Every mouthful of food was an acute positive pleasure, now that it was truly their own food, produced by themselves and for themselves, not doled out to them by a grudging master. With the worthless parasitical human beings gone, there was more for everyone to eat. There was more leisure too, inexperienced though the animals were.

Note then how well initially things work out, especially the satisfaction with which the animals ate their own food that they had produced. Also note how everyone worked:

But everyone worked according to his capacity... Nobody stole, nobody grumbled over his rations, the quarrelling and biting and jealousy which had been normal features of life in the old days had almost disappeared. Nobody shirked...

This attitude is epitomised by Boxer, whose motto, "Must work harder!", seems to help unite the animals in a common purpose as they all work together to run the farm and get in the harvest. Of course, things do not stay like this...