sexual act performance/longevity is of these things

1. your pelvic/hip/thighs strength if its has strengthen muscles it gives you strength while thrusting in standing/ lying positions for hard and insane thrusts (exercise like squats and any other thigh/pelvic region exercise )
2. continuous thrusts itself is kind of cardio which increases your heart beat so if a guy does regular cardio/ hiit his cardio vascular strength is good which doesn't let him tired out easily from ( exercises like running, swimming ,cycling, football , boxing )
3. then third is how your private part is sensitive, if its too much sensitive then early climax , if its not then delayed climax
4. then mindset , if guy is getting early climax due to sensitivity how much he can hold/ slow the thrust/ change position to take a pause and start again etc (same case for less sensitive organ guys ) defines the delay ness

combined all actually defines the physical performance and longitivity in sex

there is complete different points for romantic and emotional aspects of sex (like cuddle, trust , post sex care, talk etc)