But now be strong, O Zerubbabel, declares the LORD. Be strong, O Joshua son of Jehozadak, the high priest. And be strong, all you people of the land, declares the LORD. Work! For I am with you, declares the LORD of Hosts. — Haggai 2:4

God says'Be strong, and work, for I am with you'. Notice the order: His presence before our effort. We work, but we work from strength, not for it; we're strong in the Lord and in the power of His might. Apart from Christ we can do nothing, but through Him strengthening us, we can do all things. The joy of the Lord is your strength, so let your hands be strong — God is with you.