There you go. Now, a disclaimer, counting calories like that is not the only way, but I do find it to be an effective way. It’s really whatever you can sustain.
And you’re thinking about the Watch the right way - use it for consistent accountability. I just wouldn’t go crazy trying to manipulate your cardio as your only variable as you try to lose weight: it’s less efficient than manipulating calories and there are only so many hours in the day as you start having to do more and more. Definitely use it to set and hit your thresholds, as in the example you just gave.