with all the ppl who said they have problems keep eye contact. I'd say to overcome it, you just need to break the cycle and the easiest way possibly be would be to calm yourself down a bit more. When i was younger, having to deal with adults etc. i'd feel my heart begin pumping faster when i sat down to talk to a teacher 1-on-1 or i'd begin to use irregular body signals, look down/away etc. and tbh, lack of socializing compared to previous generations due to internet/texting etc. is probably another reason why it's difficult for so many teens to keep eye contact with someone in a conversation.
and oh yea, taking a public speech class rly helps

in staying focused and calm, cuz we all know we've seen/been one of those who looked like we took a bath while giving a speech about Lincoln