Are lisps horrible, i'm 15 and have one??

Ok youve proberly guessed by the question thative got a lisp but ive never even noticed it before neithers any of my friends but i'm15 in y11 and hav just moved schools because i moved house and my old school was way to far but now everyones making fun of my lisp wich is eve worse since i never new i had 1, now i'm watchig everything i say, its makig me realy selp concious and i can't say anythig to the other kids because wen i stick up for myself they just laugh