I don't really feel anxiety about missing flights. Flights get canceled, delayed, rerouted all the time, so the itinerary I purchase is one I internalize as some kind of suggestion of how I might get to my destination.

I also generally aim to be at the airport 45-60 minutes before takeoff. I think I've missed one flight in my life, caused by a security line delay of over an hour, but was a city pair that the airline runs basically every hour, so I still managed to get on a flight to my destination immediately after getting through security. So I haven't learned any lessons, much to my wife's dismay.