The general rule of thumb is that pilots, and fighter pilots especially, need to be supreme specimens. To put in a tongue-in-cheek fashion, if you wanted to find actual Übermenschen in Nazi Germany, you'd first look in the Jagdgeschwader (fighter wings) of the Luftwaffe, rather than the SS, typically associated with the concept of the Aryan superhumans.

So yes, fighter pilots were healthy people by birth, and they had to remain fit throughout their flying careers. For example Hans Joachim Marseille, one of the best fighter pilots the world has ever seen,

had a physical exercise regimen of pushups and sit-ups, tightening his abdominal muscles to assist in high-G turns. Tightening the muscles helped prevent a total blackout, since what pilots call a “gray out” was not completely debilitating. Initially after missions where he experienced this phenomenon, he often climbed out of his fighter, suffering none of the ill effects of exhaustion and dizziness that plagued his comrades.^[1]

Other pilots also worked out. Did they continue to do so after their flying careers were over? I cannot say. The logical assumption would be that some enjoyed working out and some didn't.

As far as your main point is concerned, let's just look at a short list of aces (the number are the ages they died):

Hartmann (71), Barkhorn (63), Rall (91), Batz (72), Rudorffer (98), Bär (43, killed in accident), Graf (76), Weissenberger (35, accident), Schuck (94), Lipfert (74), Krupinski (79), Hackl (69), Brendel (53), Josten (82), Steinhoff (80), Reinert (88), Schack (85), Thyben (84), Düttmann (77), Gollob (75), Tegtmeier (81).

They died aged 74.8 on average (note this is not a random sample). Currently, male life expectancy in Germany is 78.7.^[2] For 1960, it was 66.7.^[3] So there's no doubt that they lived longer than the average German male, even one born 40 years later.

[1] Colin D. Heaton & Anne-Marie Lewis, The Star of Africa, 2012 Zenith Press.

[2] WHO data.

[3] World Bank data.

Being a successful fighter pilot was a young man's game. In many physical pursuits an individual tends to be at their best in their mid to late 20s- consider footballers- when they have a blend of experience, intelligence/perspective, muscle mass, but are still fundamentally young. Evidence suggests fighter pilots are at their best rather at the young end of this spectrum: Albert Ball was 19, Werner Voss 20, Jean Navarre 21, George Buerling 21, Erich Hartmann 20, Walter Nowotny 21 at the time of their rise to fame- these pilots were not just successful (in both wars) but the list is selected for men who fought in especially intense and even aerial fighting.

Of course the more 'mature' fighter pilots are also there: Richtofen, Mannock, Galland, Gabreski, Bong and Sakai were in their mid 20s, and their styles of fighting tended to be more methodical and calculated. But by a man's late 20s, already his reflexes and eyesight were fading enough to make a difference.

In air combat, instincts and reflexes were vital for survival.

Aside from having a head start by achieving their fame young, these guys were looked after by one of the world's best health systems in their subsequent lives!