BMT has changed a lot since i went through. but i'll say this: it is 100% mental. you WILL do push ups - a lot. You will get drilled a lot. You will forget to do something or mess up - they are trying to break you. Once they do - thats wen they build you into the airman they want you to be.
remember - do not take anything branch related to bmt. for instance - if your Air Force (like me

] DO NOT wear a damn Air Force shirt to basic training - you'll never hear the end of it.
number two - Do not stand out. eg; wear sweat pants and t-shirt with a hoodie (if its cold or chilly) and have your hair done neatly - NEATLY. I had a guy in my brother flight who had a literal mo-hawk when we showed up. we still make fun of him for it almost three years later.
number three - a lot of yelling will be done. LISTEN. in those words and strings of insults are instructions. follow them - to the letter. You're paid to do - not to think.
number four - dot your I's and cross your T's. Make damn sure every thing you do is perfect. You will be doing push ups for tiny ass pieces of lint. You will run several miles for a fingerprint on a stall wall. Shit happens, but if you 6x check everything - you'll be fine.
number five - you may not respect them - but you live with them. if you don't like anyone - get over it. you have to live together for the next few months. If you spend what free time you MIGHT get bickering, basic will go that much more worse for you.
and the most important.
number six - write to EVERYONE. yes, get that thing dudes my age used in school.... a pen and paper and write home. write your friends. write your teachers, hell - write your congressmen for all i care. moral is the number one thing that keeps the military moving - yours must be high to get through bmt.
its a bit of a rant - but from first hand expirence, i have a lot to offer.
any more questions - message me or hit me up on steam
and i forgot the best part _____
Good luck