firemaking has always felt to me like the most interesting old school runescape skill, because of how pointless and tedious it all feels
there's not really any way to set your character going and then do something else for a few minutes, it demands the complete attention of your mouse and eyes. you must light the fires, one at a time. if you stop paying attention, you will stop earning experience. it has very little practical application in the game outside of mostly lanterns and a few quests which require it.
when you train it, you are accepting the fact that you are putting your time and effort into and almost completely pointless task. you have to accept the absurdity, become one with it. it is sisyphean, it is a confrontation with the void.
you need to become a doll, whose sole purpose is to walk westward, performing the same mechanistic task hundreds of times, leaving a trail of ash in your wake.