• you will get hair in fun new places. this is normal and fine.
• these places include (but are not limited to) if you don't already have them: your asscrack, your back, your ears, and moles. it's fine.
• some of you, dick or not, will also lose hair. this is normal, but also if you have ovaries maybe get this checked out for PCOS.
• your acne will probably change. some people get better. some people get worse. it's fine.
• your nails will probably get an infection or a fungus at least once in your life. this is fine. (but also let your doc know).
• how you gain and lose fat and where you do so will change. this is fine.
• how you smell will change. this is fine. (fishy or rotten smells mean doctor time though)
• if you have a prostate: it gets harder to pee. prostates enlarge as you age (get this checked regularly). this is fine.
• if you do not have a prostate: it gets easier to pee but not in a good way. as in as you get older, your pelvic floor muscles tend to lose some of their strength. this makes it harder to keep pee in. this is fine.
• all breasts and pectorals eventually sag, with the rest of your body. this is fine.
• a decent percent of the population will experience a cyst at least once. some of you will make up for the rest with multiple. this is fine, but keep them checked out by a doctor. (sometimes this is a condition! get checked for that too!)
• almost half of everyone gets hemorrhoids. it's a good idea to just expect them since your chances of getting them get higher the older you are. your toilet will look like a murder scene. definitely get your booty checked out BUT this is almost always perfectly normal. just eat more fiber. "but I already-" eat more fiber. and maybe suck it up and buy some hemorrhoid cream, you'll thank me later.
• yes, this means you will probably need to make an appointment for a doctor to see your butthole. it's okay. not only do they really not care but 1. they've seen weirder that day and 2. they'd far rather you see them now than later when it's been going on for forty years and now it might be colon cancer. it's okay. consider it a rite of passage.
• adults need more sleep than children. don't believe the myth that you need less than they do. that is capitalist propaganda to make you give up more of your life to the work grind, comrade.
• vitamins and medicine, something you are more likely to take as you get older, sometimes make the toilet turn weird colors. it's okay.
• if you still have your tonsils and get those little stones and get sore throats more than once a year you should plan on getting those suckers out before the tonsils cause an infection and go septic. if you're getting stones at all you should get those reevaluated every year, especially if the stones are bigger than a needlehead (or get bigger over time). it's gross and yucky. I don't care. get them looked at before you end up in the hospital.
• you'll probably need to add foot support to your shoes if you don't already do. this is fine.
• your body changes. sometimes it can feel sorta weird and upsetting that it isn't what it used to be. that is okay, and it is okay to be upset. just know that this is normal, it's normal to be upset or not upset, but don't let it hinder your quality of life. trans or cis, there is a certain level of acceptance you just gotta give your body and forgive your body for as you get older. it's okay.
• it's okay. I promise.

• falling asleep may get easier. like scarily easier. cross your arms and get comfy in a good chair easier
• if you still have your wisdom teeth and they're impacted, they might act up around certain points in your menstrual cycle. nobody told me this!
• the lenses in your eyes begin to harden more and more as you age. go get an eye exam
• you might find you have a new allergy out of nowhere. welcome to adulthood! it's fine
• a more balanced food intake will be needed to shit properly if you don't already have issues. you'll find yourself knowing what natural laxative foods you prefer (coffee, prune plums, aloe vera, flax, olive oil, strong black tea, canned pears etc) and it won't be weird
• back pain and sciatica are normal, but if it's chronic, get it looked at. not chiropractors btw. i mean an actual doctor that went to a registered medical school
• good comfy shoes are worth more than gold
• more and more you'll want some fuckin peace and quiet. this will inevitably rarely happen
• your tastebuds will change! i find myself enjoying more bitter and rich, complex flavours like super-dark chocolate now, than at 20
• posture is fake! look it up! just stand and sit in a variety of comfortable poses and move your body often. try to avoid shrimp poses though. like where you lean forward too much. they can get you so bendy that you won't stand tall for hours.
• if you look away from a topic it will feel like you're missing something, more and more. this is fine. i don't know who those new celebrities are either. you'll suddenly not care one day and it will be beautiful
• you'll never stop thanking the universe that you're not a teenager, because fuck that

The tallest mountain in the solar system, Olympus Mons on Mars. It has a height of 25 km, Mount Everest is 'only' 8.8 km tall.