“Just” is the sound of a camel getting his nose into the tent: his body will soon follow. “I’m just going to have one drink”. "It's just a little lie." "I just couldn't help myself."
“Just” is a Trojan horse bearing excuses. “I was just…..” are three little words that can defend against almost any charge or accusation. In adult relationships, when someone explains their relationship with another person by saying "we're just good friends", chances are they're more than that.
"Just" shares a root with "justification". It can be used to justify all kinds of shenanigans. Some people utter it like a magical incantation to minimize the significance of almost any event or action.
"Just" can distort reality to a person's wishes. “I’ll just be five more minutes on the computer” often turns out to be half an hour. It keeps people from having to say exactly what they mean.
"Just" is not always just.
Just do it? Sometimes, but not always.