Take the following situations for example:
Situation: Someone says: "How are you?"
My answer (lie): "Fine."
Truth: Everything hurts, getting out of bed this morning was so tiring that I need a nap to get over it and my head is aching.
Situation: Someone says: "Hey, I like your new hair colour."
My answer (half-truth): "Thanks I love this colour."
Truth: Plaquenil strips the colour from hair - so my hair grows translucent. The see-through roots make me look bald unless I re-dye my hair regularly.
Situation: Someone says: "You look good."
My answer (evading the issue): "Thank you."
Truth: I look good because I used up half the energy I have available for the day in very carefully applying make-up so I don't look like Dracula's sister.
Situation: Someone asks: "Do you need help?"
My answer (flagrant lie): "No, I've got it under control."
Truth: Yes, I need help. I am too proud/independent/stubborn/pig-headed/choose your own adjective to accept it. I will make myself sick trying to take care of things myself before I accept someone else's help.
Situation: Someone says: "That colour you're wearing really brings out your eyes."
My answer (half-truth): "Thanks, maybe I should wear it more often."
Truth: That low-grade fever I always have is a bit higher than usual, and as a consequence I have really glassy eyes.
So there it is. I am a liar. I constantly try to con the people around me and about half the time I get away with it. But before you go throwing stones, if you're a lupus patient, I bet you've told a few half-truths or blatant lies yourself.