How might I create a resettable duration counter? E.g. a "you should replace your filter"-like counter

Hello folks. Does anybody know how I might be able to create something like a “replace your filter” kind of automation/counter/warning/thing? I’ve had this idea in my head for a while where I’d like to create an HA notification/state/something based on how long my furnace has been on instead of going with a simple “replace it every 3 months”. Heck, for 5 months this year, I didnt use my furnace once!

I already have my google Nest data in HA so I can see how often I’m heating (aka using up my filters). What I can’t figure out is how I can…

  • Count up the total “on time”
  • Create a notification when over the threshold
  • Easily reset the clock

I mean, I could probably cobble together the first 2, but the third item is where it all falls apart. Any advice would be greatly appreciated!