What would you consider to be "the best years of your life"?

Yeah it’s a well worn phrase I know, unclear to me however where the true definition lies. The best years of any individuals life can be said to be behind them, if you’re of a certain age for example. It would seem confirmation of that notion lies in the belief, of some, that your schooldays are indeed the best of your life. I reckon it entirely depends, childhood & youth holds the advantage of having your whole life in front of you, which could be translated as the best is yet to come. So for me it varies from person to person. Dependant almost entirely on chance & circumstances, the way ones life pans out. You could have a lousy childhood & then lead a wonderfully enriched life in your adult years. Or vice versa. So, to answer my original question, how do you see it? Uniformed at a certain age? Or diverse complex & exclusively drawn by an individual “life pattern”?