There are fun and rewarding Engineering jobs too!
My senior year my college, my ME advisor told me “NASA is fine, but if you really want to design aircraft, and feel ownership of the machine, you need to interview with a big “Prime” contractor.
Before changing careers, why don’t you consider changing employers? Despite COVID, currently both Bell and Sikorsky are hungry for young but experienced engineers (at 35 you are still a kid at both these companies).
Both Bell and Sikorsky recently were awarded large contracts for developing two new military rotorcraft. I can tell you from experience, there’s nothing like seeing an aircraft you had a hand in designing flying for the first time.
And you don’t have to sit behind a computer all day. As mentioned already, flight test engineering is an option. But so is product support, manufacturing, and system testing.
Finally, you are at an age that can bring you rapid advancement at these companies. Approximately 30% of the engineers at these companies are age 50 and older. And due to economic cycles in hiring, there are few engineers between ages 35 and 50.
Best of luck in whatever you choose to do.