My world does not load, when I join, it is stuck on generating world

When I try to join my world, it loads with the experience bar loader, and about a third of the way there, the load bar disappears, and it does not load, it only says, ‘Generating World’ and only sometimes says, ‘Loading...’ and ‘Done!’ Sometimes, my sister has the same problem, and I have to punch her in the game if I join, until she sees the world.