When I was very young, I suffered from chronic headaches. I used to just sit in class with my head on the desk feeling completely miserable. Doctors suggested this was likely due to sinus problems. My nose was completely stuffed up all the time. After going to a few specialists, nothing ever really came of it, but I did eventually just grow out of it.

However, I continued to get these really nasty migraines from time to time throughout most of my life. It would typically happen maybe once a month at most, but it was almost always on a Sunday. I would wake up and my head would not hurt, but I immediately knew it was coming because things just didn't feel quite right. As the day goes on, I would start to feel nauseous and my head would slowly get worse. By evening I could barely move, and basically just had to lay in a completely dark and silent room, hoping I would eventually fall asleep. Typically waking up the next day with still some after-effect of it. I found a few things that helped a little, such as going outside and getting fresh air, but nothing that would cure it.

As I've gotten older, that pretty much never happens anymore - maybe once every year at most. I can't think of anything that actually changed, it just stopped being a problem.