Freedom of choice is a good thing to have. If you really want to commit future-you to the choices that now-you wants to make, there is a variety of surgical procedures that are moderately hard to impossible to reverse. But again, why do you want to give up future choice?
I'm worried about getting a woman pregnant, and I'm not sure reversible birth control is effective enough.
Use nicotine patches and porn to change your sexual preferences?
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.