enthusiastic and eager
zealous - eager
Somebody who is ‘zealous’ spends a lot of time or energy supporting a person, cause, or ideal that they feel very strongly and passionately about. While that can be a positive in some senses, ‘zealots’ are often overly enthusiastic, which makes them uncompromising and potentially willing to employ violence to achieve their aims. The term is most commonly used in relation to politics or religion.
These zealous political activists have convinced themselves that they are doing good, which in their minds excuses the harm and misery they have brought to others.
Marie is a staunch supporter of her faith, but she’s by no means a zealot. She’s far too understanding for that.
The detective tracked down the killer with a determination that bordered on zealotry. He was rightly commended for his great effort and sacrifice.