This is the opportunity 'of a lifetime'. = This sort of opportunity comes along 'once in a lifetime'. [=this is a very rare opportunity]
a baseball player's 'lifetime' batting average [=batting average measured over a baseball player's full career]
She was presented with a 'lifetime' achievement award. [=an award for all the work she has done in her life]
(..) Because I believe in you and the world you want to build. But the world you want to build doesn't get build all at once. Probably not in a single lifetime. How do we ensure your vision endures? After you break the wheel, how do we make sure it stays broken? You want to know who sits on the (..)2017 TvShow: Game of Thrones Title: Beyond the Wall Season: 7 Episode 6