What over-the-counter vitamin is best for better energy?

I am consistently lethargic. It could be meds I am taking. It could be the lay off of work (i'm a teacher) but I want to know if there is any energy boosting vitamins you recommend. My diet has not changed.

A good quality multi-vitamin, or better still something like Korean Ginseng or Ginko Biloba. Drink plenty of water and go for brisk walks. It might be an idea to check your bloods at the doctors, make sure all is ok. You could be anaemic.