Steel (one's) heart against (someone or something) informal verb phrase
To refrain from feeling compassion and kindness for someone or something.
Her ex-boyfriend caused untold suffering, which steeled her heart against other people.
She had to steel her heart against pity for fear of being hurt.
For her own benefits, she steeled her heart against people.
To stop talking or thinking about something.
To try to imagine how would you feel if you were in someone's else situation
The verb "steel" should be conjugated according to its tense.