Every new hire acts the same

I've noticed a trend with new hires. When they first start working, they are full of energy and enthusiasm. They ask a million questions and they’re eager to learn literally every little detail about their jobs. It's always great to see that kind of motivation and excitement and it gives you hope that the person will become a great worker. However, after a few weeks, they start changing. Their hype wears off and they start slacking. It usually starts with minor things, like taking longer breaks or just not putting in as much effort. Then, after a few weeks, it quickly escalates and it’s usually the breaking point where they either get fired or make a firm decision in their head whether they will respect their work obligations or not. About the constant questions at the beginning: I like it, I really do, but I just believe that the first rule about learning is just showing up and being consistent at work. Practice makes everything perfect. I want to ask you, have you figured out a way to prevent this behavior? How do you keep new associates motivated after the initial excitement wears off?