>>76285931 (OP)I'm an adult male performer so I can share some insights with you.
As other anons have said hygiene is critical, you wouldn't be surprised how unprofessional and unclean a lot of noob performers are (especially black men)
Frequent STI testing is mandatory before every paid shoot. I get blood drawn weekly and shoot between 3 -5 scenes a week depending on studio scheduling.
Drug use is extremely rampant as well, a lot of women were ex strippers that got into porn to earn more money for their addictions. With the skeezier production groups it's not uncommon for people to bring drugs or do drugs on set, I'm not a fan and I avoid those people. They're also the ones typically turning trinks between scheduled shoots which is how you get aids.
For physical fitness it really just boils down to cardio and your ability to fuck for a long time in some awkward positions. No one wants a guy sweating all over them so it shouldn't be strenuous for you to go at it for a long time.
It helps to be conventionally attractive to book mainstream gigs, but even big fat retards with small dicks have their own niche (SPH, fat guy hot girl, etc..) I shoot mainstream gigs so I'm pretty muscular but not super lean, hairy torso (I shoot porn for women mostly)
I'm not even a tall guy, on camera it's hard to tell height and I'm usually paired with short / super petite women.
Open to any questions, this is my second job I do on the side between running a landscaping business in Florida. I am married and my wife is happy with my work.