Be strong. This is repeated three times for emphasis' sake. The same exhortation was given by David to Solomon before the building of the first temple (1 Chronicles 28:10; comp. Joshua 1:6, Joshua 1:7, Joshua 1:9).
Haggai seems to suggest comfort in the thought that such admonition was needed at that time as well as now when they are so depressed (comp. Zechariah 8:9). And work; literally, and do; ποιεῖτε: facite, The word is used absolutely, as often (camp.
Isaiah 44:23; Amos 3:6, and note there). Here it means, "Work on bravely, finish what you have begun." I am with you (see Haggai 1:13, and note there). The consciousness of God's presence gives confidence and strength.