Zealous
means,

Passionately excited and eager, or warmly engaged in the pursuit
of an object
(such as the salvation of souls,
the worship of God,
the spiritual gifts,
good works,
etc.).

... Looking for that blessed hope, and the glorious appearing of the great God and our Saviour Jesus Christ; Who gave Himself for us, that He might redeem us from all iniquity, and purify unto Himself a peculiar people, zealous of
good works.

Titus    
2:11-14