In the next few days I'll be going to my local Aviation Doctor to setup and appointment to do my 3rd Class Medical Exam. One question.
What all do they do to you during the exam??
You will be required to pee in a cup (looking for sugar or blood in the urine), get your vision and hearing checked, and the doctor will conduct a rather simple and brief physical exam. Some include a rectal exam of you prostate but that's optional. The hearing test for 3rd class can be as simple as the doc asking you what he said when he talks quietly while facing away from you (in case you can read lips!). The vision test is usually done on a machine like and includes checks of your near and far vision, your ability to distinguish between red and green, plus a check on your preipheral vision. The color test is difficult for folks with normal vision but doable for most. If you have trouble with that there are alternatives but it's best if you can pass the first test.
He will also go over your answers on the form you must fill out on your medical history.
And on that form you must disclose all sorts of stuff you probably won't remember like every doctor visit you've had in your entire life, and especially any hospitalization or surgery. You also must disclose any incidents where you were charged with anything that was alcohol or drug related even if there was no conviction as well as any times your driving privileges were suspended or you were required to attend remidal driver's training (whether or not related to alcohol or drugs). There's a big list of medical conditions ranging from heart transplants to hay fever on which you have to indicate if you've ever been diagnosed.
When you fill out this form, DO NOT LIE or OMIT ANYTHING, but if you think you should check a box in the affirmative, leave it blank and ask the AME whether or not you should check it. If you provide false info (diliberately or inadvertently) you can get into big trouble, including the loss of all flight privileges you've earned when the error is discovered, even if the error doesn't surface until years later.
If you've ever had medical issues with things like heart disease, diabetes, cancer, or any chronic condition it would be a good idea to bring whatever medical records you have on that. You should also be able to ask the AME beforehand what records he wants/needs to see.
Given your young age, I expect the exam will be easy to pass unless you have a known medical problem.