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]
(..) Mike was just saying, how bad is the take on MGM's new film. Howard, Rad, Steve! Comon over here. Is it not the best films you have ever heard in your lifetime? Am I right? Howard Fox, Bobby Dorfman. Howard was the two time Academy Award Winner. Wow! Congratulations! Thank you. (..)2016 Café Society