When you get it injected and you are deficient. I didn't feel a boost of energy but I do feel like I can work longer but it's not like an electric super power feeling the moment I injected it as some people describe. For me it's been about a day and I'm not sure if I have gotten used to the b12 but I don't feel like I feel it anymore as much. I took 1mg. When do I feel like a new person? The initial effects were already not so obvious. I know it's early but at what week do you feel like a constant boost in energy that's there at all times? how was it for you?