I'm not subject to the whims of anything except what I just asked for.
I can also cancel it just as easily, if it's exhausting. Which--I'm finding it hard to understand why it would be.
I don't schedule my life like that at all, I kinda wander around all day. But the idea of a reminder that I specifically asked for? It's the only kind of reminder I want, actually. It'll keep me from the actually-exhausting habit of checking my watch or wondering how long it's been.
I don't use a sauna. In my imagination some people might prefer to stop their sauna usage when it feels right. That doesn't require checking a timer.