It depends on the paperwork you signed when you started the job (and since then), as well as the local laws. Many states, including California if I'm not mistaken, have specific provisions that prevent a company from owning unrelated things you do in your spare time. In those places, they can't "own your brain".
The place where this gets shadowy is when you say, "I write programs that make life easier for my company." This sounds like it's clearly related, despite your earlier comment of, "this job has nothing to do with software, IP, or programming."
If I were you, I'd start by re-reading the stuff you signed when you started working there. If you want to be sure, your best bet is to talk to HR and/or your supervisor. If you can, get them to sign some paperwork saying that any software development you do belongs entirely to you, and if they're using it, it's done so either with a paid license (they end up paying you extra for your moonlighting software work) or with a free license (they don't pay you, they can still keep using it, possibly including some or all updates you make, but it's wholly owned by you). If you can get it in writing, you're pretty safe.
One other thing I should mention is that it becomes far more complicated if you're using their computers or other equipment to do your work. If you want any hope of keeping it for yourself, always use your own computer, and your own software development tools. (Buy your own copy of Visual Studio, etc.) And don't do the work on site or on their time. If you violate any of those, then it is probably owned by them regardless of what else happens. Basically, just make as large and clean of a separation as you can.