How to respectfully look someone in the eye?

I try to look ppl in the eye when they talk to me but all I'm focusing on if i is look phony, or worse, like an obsessed stalker so I dont know what to do because when I dont look ppl in the eye I'm worried they think I'm not listening, I'm bored, confuseed Or just dont care. I know they say short but frequent eye contact is the least offending but I still feel like theyll think im not listening and I m not sure when to loook or look away