I'll let some of the younger folks talk to the "initial" flight physical. But the annual is usually a confirmation that you are still "Physically Qualified" to fly. Some things to consider - pay attention to your hearing (or, in my case, hearing loss). In time, you will have some hearing loss and eventually, may have to have your hearing "re-baselined." I've been re-baselined "a few" times. If you are on a waiver (of any kind), they will review and submit to NOMI a waiver request each year. Medical is getting better about computer data bases and tracking your previous medical history (from another base for example). They will also track your blood work (cholesterol, etc), eye sight, etc. As a side note, be careful about what you "confess" to your flight surgeon. There are good ones and absolutely horrible ones that can end your career on a whim (just because you confessed about your sensitivity to allergies for example). You go into medical "Physically qualified" you want to leave medical that way as well.