I've been thinking about "just" so much it no longer looks like a real word to me. It has quite a few different meanings - is it superfluous in all those meanings?

I can understand removing it in a sentence like "Just checking in to see if you are ok" or "she just ran a few miles". But what about "she applied just enough force to flip the lever" or "she's just a baby" (where just could be replaced by only, is that an improvement?).