I am 71 years young and started getting interested in self hypnosis when recovering from a heart attack back in 2004. I first used it, while still in hospital, to bring down my temperature. Otherwise I would have had to suffer a dose of antibiotics which I was, and am still, totally against.
I used it again during my recovery from a double heart bypass later that same year to alleviate the pain after the sedatives had worn off.
And in 2013 I used it once more after my Colostomy, again to alleviate pain. And I continue to use it daily to control my stoma .
On the non-medical side I have used it to improve my communication with my dear wife of 45 years
As far as I can make out, self hypnosis is just getting into a state of relaxation then (and this is the hard part) finding the right visualisation with which to instruct ones subconscious.
As well as Roger and Mark's downloads I have found great help with understanding the subconscious and visualisation in daily study of a work called the "Master Key System". Though curiously the author "Charles F Haanel" did not believe in hypnotism!