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]
(..) I remember yours. Here you go. Eat this. You must be hungry. No. I put a spell on it so it'll give you back your strength. Just eat it. Have some more. You'll be all right. - Just stay out of trouble. - Thank you, Haku. You're a good friend. (..)2001 Spirited Away