Knott's Berry Farm

Tessa and I were able to relive childhood memories and hang out at Knott's Berry Farm a few weeks ago. We were both SO excited to ride roller coasters, eat Dip N Dots, and just hang out for the day. The park was deserted. The workers were literally begging us to go on their rides because they were bored to tears. (Maybe not literally.)
It was such a great day. We did everything we wanted to (besides Montezuma's Revenge) and we had so much fun hanging out together. However, we both came to the same conclusion at the end of the day...
We both got headaches after all the roller coasters we went on. What happened to hitting 10 roller coasters in one day and being fine? Guess I'm not 16 anymore.