From Longman Dictionary of Contemporary Englishgo the extra milego the extra mileTRY TO DO OR GET somethingto try a little harder in order to achieve something, after you have already used a lot of effort The president expressed his determination to go the extra mile for peace. → mile
Examples from the Corpus
go the extra mile• And it diminishes the employees' desire to go the extra mile when supervisors need them to.• The President vowed to go the extra mile for peace in the region.• All this when her only motivation was to go the extra mile under all circumstances. 