What does "I don't have it in my heart" mean? [closed]

in one's heart OED

in one's inmost thoughts or feelings; inwardly; secretly; at heart.

As in:

2001 J. Boyle Galloway Street 101 I know in my heart that in a real fight he would beat the bejesus out of me.

So, What does “I don't have it in my heart” mean? It means thoughts or feelings as referenced in the conversation are absent in the speaker.