Play Fighting is almost essential to building physical truest IMO. Not just trust in the people you train with, but trust in yourself. Knowing what you can and can't take safely.
People that have never engaged in "horseplay" or play fighting are very hesitant, and concerned for there safety when they shouldn't be. Not just in martial arts, but often in other things. SOme people are scared of falling. Not neccessarily from a height, but just slipping or tripping. After falling thousands of times in playfighting, I imagine the fear of falling would be gone
I trust everyone I train siwth fully. I know that anytime they do a lock or a choke on me, they could cause serious injury. I also know that none would do that intentionally. I am also pretty sure that if an accident did happen, and one did break something, once I got out of the cast I would still trust them to do the same lock.
I also trust myself, I know that if I get hit, it might hurt a little, but I won't get injured. I know that I can take a pretty solid hit and keep going. While I don't like being punched in the face, I trust that I will still be standing after a few rounds of it, and if not, I'll get up soon enough. With gloves and in sparring, that is pretty unlikely though, even when going hard.
I think a little wrestling and boxing are one of the best ways to build trust, and self-confidence. Everyone should try both in some form for at least a while
