ah Zmj--you remind me of my first French teacher (a nun) who would come by and try to pinch our cheeks. those of us who cowered and cried (when pinch) sometimes got extra points.

she maintained that, if we were doing our homework and practicing prononciation, our cheek muscles would be sore --because we needed to learn, not just words in our heads, but to use new muscles in our faces (cheeks) to make new sounds..
Especially words with R and U.

if we didn't ache from practice, she would make us ache with a good pinch!
(now days, i remember almost no french.. but i think i can still make the U sound of luna (i feel myself using facial muscles that i almost never use!)