The reason most people hate tough feedback is they feel demolished by it. It is like they visualize you sitting in a room and judging them as inadequate.
So, the usual “sandwich” approach doesn’t work. The recipient is skeptical and doubts what you said.
Instead of focusing on what you need to say, focus your energy on how great this person is or could be once this small hurdle is overcome.
Let them see your belief and faith in them being able to make changes.
Ok, I know you may be thinking, “well that won’t work with Fred because he is always angry when you give feedback.”
But try it. Just for the next two weeks. Every time you need to give feedback START with the assumption the other person wants to always perform at their top level, and ASSUME the feedback will be well received. You will be surprised at how much difference your change in energy will change the conversation.