How do you know what to follow your gut or your heart?

I've pondered this many times and I really just don't know. I'm at a draw. So wondering what other people think. In some situations people would say without a doubt go with your gut, but if going with your gut breaks your heart and makes you spend countless hours thinking things over and over again then wasn't that the wrong choice? Or you go with your heart even though you know in your gut that not everything is right yet you hold out hope that things can or will be different? I think I am the latter of the two types. I go with my heart until my heart doesn't feel it anymore even if I know in my gut that something isn't exactly right in the end I always say that I never have doubts that way. It's hard to be sensible. Because I would always look back and wonder if things could have been different. If I go with my heart and my heart changes then I don't look back and wonder and have regret. The heart takes longer to fade though and can go back and forth so it's sometimes tricky. What's your thoughts?