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]
(..) - Well, thank you. - That sure it would damage my back. - Yes indeed. Thank you again. Hey, waits a moment. He/she takes this, they will maintain your dry feet, any problem calls me, the number is inside the boots. Thank you. Now I began to walk... ... TOWARD THE WILD THING. Hello... (..)2007 Into the Wild