Following on from fireeeeeee's answer to this question, the example "I eat cereal for breakfast" and the descriptions concerned, please let me know what is the difference between that and the sentence "I am eating cereal for breakfast" being used as a temporary action for present.
The present simple is used for quite a few different things, but it's not usually used for things happening right now: see this British Council page for more information. For your example
I eat cereal for breakfast
This usage of present simple would be taken as a habitual action... you usually eat cereal for breakfast.
The present continuous is used for things that are happening right now, so if somebody said - maybe on the phone:
I am eating cereal for breakfast
I would assume that the person had put down his or her spoon to answer the phone.