"In my younger years, early days, early years, and earlier years"?
Summary of the comments:
"Until recently/until a few years ago" or "I always used to [think/believe] but recently I ....". It might depend on how old you are now. If you are 87 you would say "All my life I have [believed ]....". But if you are 21 you could say "As I grew up I always [thought]..."
-- Mynamite Aug 20"for my whole life until recently," conveys what you're after. A slight variation would be, "for most of my life until recently," which I suppose is technically more accurate.
-- G Tony Jacobs Aug 23