So I have a lisp...

So ever since I can remember, I have had trouble saying sibilant sounds such as S and Z and it has gotten to the point where I am really sick and tired of having this issue. This is going to sound crazy, but I've almost entirely avoided using words with the S and Z sounds if possible because I am too embarrassed of my lisp.

I'm now stuck in a position where my family and friends don't think that I have a lisp, because I mostly avoid it, but I really want to go about correcting it without having to go to family and ask... any ideas?

I would love to do exercises at home to practice getting rid of it, but I'm not sure on what I can do. I've heard of the smiling method, but my S sounds very hissy and almost like a stereotypical homosexual sound (it's the best way I can describe it, sorry). It's really depressing me...