system
Given the following post, respond as if you're commenting on Reddit:
human
How hard is it to learn Dresdenverse magic without being taught?

Assuming that you don't have any books or knowledge of magic in general.  You just realize at some point that you can do inexplicable things.
gpt
no really that hard, sadly. The magic in the dresdenuniverse is basically changing and effecting your surrounding with energy provided by your emotions. So if you will it hard enough and your emotions are strong enough it will just happen. But here lies the risk of doing magic untrained if teached correctly a wizard chooses a dead language to trigger his spells, why? Because it gives an isolating barrier between your mind and the forces of live and universe you are manipulating at that moment so an untrained natural is at heavy risk to trigger a spell by excitement and to fry his brain out in the process. Secondly a professionally trained wizard has one attitude drilled in to him- discipline of mind to control the forces you conjure and steer. Imagine you are a teenager who because he just thought it is cold started a fire out of nothing in his room. You are scared you don't know what is happening - that is strong emotions and a lack of strong will also known as magic going wacko. 
*So short yes you can "learn" magic but the training is more for the sake of your survival and protection of others because without 90% of young wizard and up burning down a house before the forces of magic fry out there brain changing them in to vegetables for the rest of there life.