Sources: Various
It is not too late to make your plan to raise awareness of the unreached. A Third of Us has lots of free resources in English, French, Portuguese, and Spanish (though registration is required to access them).
And why just stick with one day? Download the Joshua Project Calendar and pray for a different people group each day all year. Or check out their new interactive prayer map.
Need some inspiration? Watch the music videos for Facing a Task Unfinished (Keith and Kristyn Getty) and I Then Shall Live (Gaither Vocal Band). The last verse that begins “The Bread of Life…” always gets me thinking about the unreached.