I got that experience through dating dozens of men for six years after college, getting an entry level magazine job at 21, working in the fiction department at Good Housekeeping and then working as a fashion editor there as well as writing many articles for the magazine.
I would, however, start writing fiction about 10 years before I actually did, because it's such great fun to do, many times more creative than nonfiction.
Surely the whole point of writing your own life story is to be as honest as you possibly can, revealing everything about yourself that is most private and probably most interesting for that very reason.
The only way to find out if you can write is to set aside a certain period every day and try. Save enough money to give yourself six months to be a full-time writer. Work every day and the pages will pile up.
Have some sort of a private place to work in. Put up a sign to keep from being interrupted. Mine says: "Please, do not knock, do not say hello or goodbye, do not ask what's for dinner, do not disturb me unless the police or firemen have to be called."