One of the most important things you can do when you're with another person is to listen to what they are saying. This requires you to give them 100% of your attention while they are talking.
Likely, you have fallen into the habit of formulating what you are going to say next while the other person is talking to you. Possibly, you believe that you've mastered the art of "thinking through what you'll say while pretending to fully listen to them". If so, you're wrong.
Ask yourself this: Can you tell when someone else is thinking about what they'll say, rather than fully and actively listening to what you're saying? Of course you can. Humans have spent millions of years evolving the ability to read body language of other humans. You're not fooling anyone.
A key to breaking this habit is allowing for small pauses after the other person has finished their thoughts. Often, we think this pause is awkward. Or we may fear that we won't appear smart if we're not rushing to fill the void. But neither of these are true. If you're fully and actively listening to the other person, then you'll need a second or three to gather your own thoughts. And that's okay. In fact, the other person will both realize and appreciate this for what it is - the gift of truly listening to them.