He Lived A Lifetime
It is a generally accepted fact time seems to get faster as one gets older, perhaps the explanation for this lies in the theory of relativity. According to relativity, nothing is absolute and all judgments of measurement (length etc.) are based upon comparisons (an inch is shorter than a foot, but what’s an inch by itself?). One’s life is all the time one knows and thus is the only basis of comparison for making a judgment on the length of time. So when you’re 1, a month is 8% of your entire life, and hence seems to be a very long period of time. But when you’re 20 a month is only .4% of your life and thus seems much shorter than it did when you were young. This would account for why time seems to get faster as you get older, each individual moment seems less compared to how long you’ve lived.
When you die and your life is complete, you have only lived a lifetime. You have nothing to compare it to so it is simply a lifetime in length. A child who dies, a teenager, an adult, they all lived a lifetime. To each individual the length of existence seems the same, because it is all the time that they’ll ever know. It is total and complete. It is a lifetime.

