Oprah Winfrey undoubtedly has a lot to be thankful for, but as she marks her 70th birthday on 29 January, we take a look at what she says has given her all that she has - gratitude.The media mogul and Oscar-nominated actress once famously said she wasn't grateful because she's "a gazillionaire", but her habit of practising gratitude was "the way I got to be a gazillionaire". While she has almost unprecedented levels of wealth and success (particularly for a woman), she came from very humble beginnings and was raised by her maternal grandmother on a pig farm in Mississippi for the first six years of her life.