What we can glean from this verse is that God’s grace, His unmerited favor, can be waisted; offered in vain.
However, it should be used as a catalyst and propeller to drive us work hard, for good works as Paul shares. That in one sense it was He that was working and co-operating with God’s calling yet at the same time, it was the marvelous fresh grace which was empowering him.
Marvelous grace, fresh each morning. Let’s abide and relish in it but never get complacent or allow it to be an excuse to willfully sin.