Binding function to $interval - angularjs

Question

I have a service that I'm using to manage the state, like the time since a user last did something. In another directive, I use the interval service to check this state (lastActivity), but it's not getting updated:
// myservice
start() {
this.$document.on(this.DOMevents, this.updateActivity);
}
stop() {
this.$document.off(this.DOMevents, this.updateActivity)
}
updateActivity() {
this.lastActivity = new Date();
}
// other directive
$interval(() => {
console.log(myservice.lastActivity.getTime()); // lastActivity is just a javascript Date
}
}, 1000);
I think this is the closure problem in that $interval gets myservice before it runs every 1000 ms so the time is always the same. Is there a way to pass that in to get updated? I see in the docs https://docs.angularjs.org/api/ng/service/$interval
that there is a pass option as the last parameter, but since I'm using TypeScript and an older version of Angular, I won't be able to use this feature. Is there another way to do this?
Maybe this explains my problem clearer:
var now = new Date().getTime();
$interval(() => {
console.log(now);
}, 1000);
I have some service that is keeping track of time amongst other things. In another directive, after a certain amount of time has passed I want to check this value and do some logic. Problem is, now is always the same time. So in myservice, the lastActivity time is not getting read properly in the $interval function.