Who are the 144000?

 And I looked, and, lo, a Lamb stood on the mount Sion, and with him an hundred forty [and] four thousand, having his Father's name written in their foreheads.  

The 1335 Day Prophecy

This is the time of the Latter rain, Jacobs Trouble, Plagues and the Second Coming of Jesus.

Prepare

How can I be prepared?