"Who despises the day of small things?"
The Temple of God was in ruin, destroyed during the Babylonian invasion about 70 years earlier. It needed to be rebuilt, but that was a pretty big job. Who would do it? Zerubbabel, that's who. He was the guy in charge of rebuilding the Temple - the guy that God wanted in charge.
Most people, though, were not enthused about this rebuilding process, nor had the confidence in Zerubbabel. But, God is God and God can do what He wants. God spoke through the prophet Zechariah and said, "Not by might, not by power, but by my Spirit." Which means, "This Temple is not gonna be rebuilt by the brute force of people nor will it be stopped. That which I want done, will be done by My Spirit and Purpose."
And to really drive this point home, God told the people, "You'll see when it's finished that I have done it. And then you won't despise My Word or have contempt for My servant, Zerubbabel." (That's a wide paraphrase)
Listen, if God wants something done, no one, absolutely NO ONE can stop it. There's no need fighting it or ignoring it - especially if He wants you to be a part of it. Jump in with both feet! Take a big leap forward! Watch what God will do and don't despise or have contempt with His plans.
What seems like small beginnings one day, with God's Spirit, will be an unimaginable glorious day when He's done.
Have faith and believe!