That has been a staple of Christianity. It was a command for all Christians to be on the watch.
When I was exiting the WT, two elders visited my home for an encouraging visit. They told me that the End is just around the corner. I responded, "Well, what does that mean? Brother Rutherford told the kids in the 1920's to remain single, because Armageddon was so close. So, I don't really know what you mean when you say that it's very close."
The PO told me that I was being cynical. <------- I call it being realistic. The cemetaries here are chock full of dead people who believed that they were living during a special time. Turns out, they lived and died, just like the billions before them.