Now that the quarterback has recovered from his injury, this week the team will be functioning 'at full strength' again. [=the team will have all its players again]
We are negotiating from a 'position of strength'. [=from a strong position; from a position that gives us an advantage]
He didn't mean to knock you down; he just 'doesn't know his own strength'. [=doesn't realize how strong he really is]
(..) It's still a story without an ending. What about now? Now? I don't know. I know I'll never have the strength to leave you again. And Laszlo? You'll help him now, won't you? You'll see that he gets out. Then he'll have his work. All that he's been living for. (..)1942 Casablanca