So... I am writing a "series" of novels (similar to Redwall in that they are set in the same universe/country, but not necessarily connected to each other) and a large part of that world is a form of "magic".

Basically, there are some people (maybe 20-3-%?) who are born with the ability to affect the world around them through the use of "magic" (I am thinking I will give it another name), they are called either an enchanter or enchantress. Each enchanter has the ability to learn to use magic, but will not necessarily be "good" at it. It takes time, effort, and energy.

So, what I am having trouble with is this... I am not sure how to put a "stopping point" on the magical power. Like... none of the enchanters are all powerful, and I don't want the main character relying solely on her magic to get out of every situation... so I am trying to figure out what sort of limitations there should/could be on their power.

Any ideas?

Where's the source of the magic? Is it drawn from their own energy, from an exterior source, or does it work in some other fashion?

I would say it's drawn from their own energy and produced through the use of "enchantments" which are just word patterns. Though I haven't really pinned down what the energy amount would be, like whether certain types or amounts of magic use more energy than others...

One of the easiest ways to limit magic is to simply decide that certain types of magic, while theoretically possible, take more energy than anyone could possibly have.

Does magic use the same energy source as non-magical activities (running, jumping, etc.), or does it have its own separate source?