He 'kept/maintained his cool' [=he didn't get angry or upset] even though it was clear that he was being unfairly treated.
He was struggling to 'maintain his cool/composure'. [=he was struggling not to become angry or upset]
They barely had enough food to 'maintain life'. [=to make it possible for life to exist or continue]
(..) The submissive will not enter into sexual relations with anyone other than the dominant. The submissive will eat regularly, to maintain her health and well-being The submissive will conduct herself in a respectful manner. To the dominant, and so only address him as Sir, Mr Grey. (..)2015 Fifty Shades of Grey