From Longman Dictionary of Contemporary Englishwork up phrasal verb1BECOME work up enthusiasm/interest/courage etc to make yourself feel interested, brave etcI’m trying to work up enough courage to go to the dentist.2HUNGRY/WANT TO EAT work up an appetite/a thirst/a sweat to make yourself hungry or thirsty, or make yourself sweat, especially by doing physicalexerciseYou can work up a really big thirst playing tennis.3ANGRY work somebody up to make someone very angry, excited, or upset about somethingwork yourself upYou’re working yourself up again.She had worked herself up into a state. →worked up4work something ↔ upIMPROVE to develop and improve something such as a project or a piece of writingJack took notes which he would work up into a report later. →work→ See Verb table
Examples from the Corpus
work yourself up• You are working yourself up again.• But Nick was working himself up into one of his states, and she had to harden her heart.• When I try to protest, he works himself up more.• You don't have to work yourself up over this.