When the mind calms down, be careful. The calm mind is like a drug for the yogi; when they get it, they enjoy it.
When the mind calms down, you need to remind yourself: What is the mind aware of? What is the mind knowing? Anything else? You need to remind the mind a bit; and then the awareness wakes up.
Don’t let the awareness rest; ask: ‘Anything else?’ and continue to be aware. You’re not used to be aware all the time; that’s why the mind wants to rest after a few hours of mindfulness.
Now, you need to know that you have to be aware all the time. You have never done it before; therefore awareness also wants to rest.
So, don’t let the mind rest, try to continue to be aware.