Idiom: To have a change of heart; used as a verb

Example:
Maria: So what do you think of the puppy
now?
Neil: Now that he’s at home, I admit, he
is pretty adorable. And you’re right, we did have enough room for a pet.
Maria: I’m glad you had a change of heart. I know you didn’t want a dog at first, but I
think we made a good choice.
Neil: So do I.

Meaning: The expression “have
a change of heart” means that someone changes his/her mind on a
decision or opinion, usually from a negative to a positive. 
In the example
above, Todd has “had a change of
heart” because he didn’t initially want a pet.  But now that they have the
puppy, he’s happy about it.

www.languagesystems.edu