First, congratulations on taking personal responsibility for your health. It's important. This should not be a big deal. If you get a component doctor, he should do the following:
Take a complete medical and family history.
Ask questions about your current life style (diet, exercise, medication, etc.).
Inquire as to your current sexual activities (including, but not limited to, the ability to get and retain and erection).
Sleeping habits ... the amount and quality of your sleep ... rather you get up during the night to take a piss.
After that, the doctor will either ask you to undress completely and put on a gown, or undress to your boxers, or take off your shirt only, or strip naked and have a seat on the exam table.
Next, ears, nose, and throat. Feeling of the limp nodes. The heart and lungs. Then palpation of the chest. Next, testing of the arm and leg joints.
At this point, in the event you still have anything on, the doctor will remove all remaining clothing and commence to examine your penis and testicles, at which point he will ask you to stand up for the "cough" test, which will determine whether you may or may not have a hernia.
Next comes the tricky part. At your age, the doctor may or may not which to establish a prostate "base line". If so, you will be required to bend over and spread your butt checks, where upon the doctor will insert his gloved lubricated index finger into your anus to feel your prostate, all the while examining your rectum wall. Takes about 20 seconds.
At this point, you may or may not have a full blown erection, but don't worry if you do. It's what men do. Good luck, Sir.