your/somebody's heart is not in it

(one's) heart isn't in it

One is not emotionally invested in something. I used to love running, but my heart just isn't in it anymore—that's why I quit the track team this year. I can tell by the way you wrote this that your heart wasn't in it. Is something distracting you?
See also: heart

your/somebody’s ˈheart is not in it

somebody does not give all their enthusiasm, interest and energy to something: He agreed to write the book for a large sum of money, but his heart wasn’t in it, and it was never finished.
See also: heart, not