I seem to pronounce my s's a bit longer than I'd like, and I'd like to stop it. I asked my mum about Speech Therapy, but she hasn't said anything. Do you have to get surgery to ger rid of it or is there an easier way you can do yourself?
To remove your lithp, athk a thpeech therapist. Seriously, speech therapists can help with pretty much anything. I had an absolutely awful stutter, it got a little better after school therapy, but private therapists are obviously better than school ones. I honestly do not know any surgery that would fix a lisp. As for doing something yourself, find excersizes to do in your free time. Repeat words and phrases with "s" in them and concentrate on making enunciated, short "s"es.
Go to speech therapy, even the ones at school. I have a slightly bad lisp (that was caused by jaw problems) but had a serious problem with my "r"'s. Speech therapy worked for me during middle school when I actually buckled down about it. In elementary school, I thought speech therapy was just a place to play games and have food (because that's all we did). I second the above post. Find online exercises/Youtube videos. Those helped for me as supplements.
Coming from a dylexic kid that had a lisp in school. Speech therapist even are achool are your best friend. It's really not as hard as you may think it is but it's hard to figure how to fix it. I guess that's what professionals are for