Maybe the old exercise we used to use for art classes would help you begin to draw in a more relaxed way.
I think this came from Drawing from the Right Side of the Brain ... or some book like that.
In drawing a chair:
Don't draw ... draw the negative space around the chair ... and maybe even draw it upside down.
Sorta like that old shadow picture where you had to look at the open spaces to see the work Jesus as all the darker areas were what was the negative space around the word.
Wish I could state it better. Maybe someone else can.
It all comes down to practice, practice, practice. Then dropping those negative comments in your head about your work.
ali