Accidentally eating a piece of moldy food can turn a "look at me eating leftovers like an adult" moment into a "holy shit I've got food poisoning" moment pretty quickly, but is consuming mold really all that bad for you?
The short answer is no, you're probably not going to die from eating mold; you'll digest it like any other food, and as long as you've got a relatively healthy immune system, the most you'll experience is some nausea or vomiting due to the taste/idea of what you've just eaten. That said, this stuff is definitely not good for you, and if you're allergic to mold, it can bring on uncomfortable symptoms including irritation of the eyes, nose, and throat.
What's more, although common bread mold isn't especially harmful, there are some dangerous molds out there which can be detrimental to your health. In fact, a few of them can produce poisonous substances known as mycotoxins, the nastiest of which (aflatoxin) can cause cancer according to the USDA. That said, contamination tends to occur farther up the chain than your kitchen, primarily appearing in grain and nut crops, so your regular household mold probably isn't aflatoxin-related.