Good genes and a whole lot of good luck combined with better living conditions for the upper class of course.

In those days, having 12 children and losing 8 of those to all sorts of diseases ranging from the flu over pneumonia to malnutrition were the rule rather than an exception. Only the strong survived. Natural selection. Dying of the same as an adult also, compounded by degenerative diseases, exhaustion, war, famine, poverty ...

So to answer your comparative question: you and your friends are just the lower to middle class of those days. You already have a much more increased life expectancy than your ancestor counterparts thanks to scientific advancements of the last 40 years.

Why did Bush, Kissinger, Brzezinski, Churchill ... the queen of England become so old? They're political elites with better, less stressful or exhausting lives who only get the best of the best day in and out ... with your tax-payer money, blood, sweat and tears.