You've got to imagine vividly what movement you want to accomplish. Create a "perfect you" in the image.
Believe in yourself.
Don't think you WANT to achieve.
Think you've already achieved so you "do" what you want to achieve already.
I want you to emphasize on what you do, not what you
WILL do or you WANT to do. These will remind you and emphasized that fact that you CANNOT do it yet.
For example, you are working on fumikomi now.
You must
burn an image of successful fumikomi in your brain.
And YOU are the one doing the successful fumikomi, not your sensei or other people. You are doing it. Imagine that strongly.
Every day and night.
You do the perfect fumikomi.
If you fails to do so, don't blame on yourself.
Just think...
"It's not like me! I do this (successful fumikomi) all the time."
Because you do that in your image so don't deny that.
Learning a new skill is always hard. But instead of emphasizing on your failure, we emphasize on ourselves who are succeeding and kicking arses!