I think my energy comes from within (unless I unknowingly pull it from somewhere).
Usually I would be walking around in the dark living room with only the lights in the fireplace.
Talking to myself and perhaps finishing off a can of beer and when talking to myself I am working up my emotions and then I will feel my hands, not throbing but a strong steady buzzing energy feeling and then I'm ready to send off spells. The buzzing feelings in my hands then ceases when I finish with the sending of spells.
other times I use emotions such as anger to accidently cause some effects. But lately I have some success in doing a controlled "done on purpose" anger and hexing.
I understand what you are saying, Exile. I don't necessarily have to pull energy from anywhere or anything in order to manifest my will. As was noted by others in this and similar threads, however, I do not have an unending supply of personal energy and, thus, must occasionally channel through another source. The important thing is, that if I need it, however, I know how best to get it for me.