I didn’t have Liz’s problem, but I had a lisp. Had to go to a speech therapist for a while. She was set up right in my school, so I ‘d just go for a few sessions where she ran me through ’s’ ‘z’ and ‘th’ sounds until I could get them right. Now and zen I can thtill thlip ip. I have trouble with words like ‘synthesizer.’
And, although it doesn’t have much to do with the lisp, I can’t manage the phrase ‘edited it.’ I get a few too many ‘dit-dit-dits’ on it.