This works so well. I worked with an AFF student who was having a very difficult time with Cat C. She tried three times and the jumps did not improve, she was so stressed about everything. Husband and I (both AFF I's) took her up and did a no-pressure, relax and have fun jump. Her priorities on that jump were to fall, smile, pull, flare and have fun. After a (textbook) exit and some practice touches, I let go and flew around in front of her. I then geeked the shit out of her, smiling, laughing, sticking my tongue out. Just seeing me doing these silly things changed everything for her; skydiving was fun! She smiled and laughed back at me, finally able to relax mentally and truly enjoy the skydive. Husband even let go of her and she flew stable, no turn issues, for the rest of the skydive. She finished her AFF jumps with no more repeats.
If the things that others have suggested above (all excellent advice btw) don't work for you, this type of "relax and enjoy" skydive very well may help.
Don't give up! Remember you can only fail if you don't try.