Take to heart means, taking everything in serious. IF somebody jovially says something to you if you take it seriously it is called "taking to heart"
What Does Take To Heart Mean?
Its an idiom and it means to take something seriously.
The phrase or idiom "take to heart" refers to being deeply upset by something or to take something personally. It means that something has affected one deeply. An example can be seen from the movie Elizabeth where Sir Francis is advising the Queen when attempts are being made on her person and throne by saying "A prince should take these matters so much to heart that he does not fear to strike those who are closest". In other words he is using the phrase to move the sentiment of his Queen to act. It means that she should not take the events lightly.
An example of its use is "The old man took his sons imprisonment to heart and died soon after", or "Should we take to heart all these past insults or let bygones be bygones".
An example of its use is "The old man took his sons imprisonment to heart and died soon after", or "Should we take to heart all these past insults or let bygones be bygones".