"excited at something" is incorrect. "excited about something" = "excited at the thought/prospect/idea of something" "excited by something" = "excited to do something" "excited by something" means something excited you. (Keep in mind excite has different meanings). You look forward to doing something. "excited about something" means that in regards or concerns to something, it interests you. http://www.oxfordlearnersdictionaries.com/us/definition/american_english/excited http://ell.stackexchange.com/questions/14779/excited-about-something-or-excited-by-something