"It never lasts long"

I was explaining to my mother that her grandson always sleeps better in our bed and rarely spend a whole night in his own. He still comes and joins us in the middle of the night, whether it is because he has nightmares or he simply wakes up. I do find it hard sometimes, as Wolfie takes a lot of space for somebody still small and he often kicks in his sleep. But my mother told me: "Enjoy it while it lasts, because it never lasts long. One day he will just stay in his bed and will not bother you and you will miss these moments." I keep it in mind every time Wolfie kicks me.