“My ability (and desire) to drink alcohol. Back in college, I could drink until 3 a.m. and wake up early the next morning to write a paper. Now, in my early 30s, alcohol really affects my sleep. Plus, I’ll be nursing a headache after a mere two glasses of wine. I also don’t have any interest in drinking the way I used to. I’ll enjoy one cocktail with dinner, and then I’m done for the evening. The idea of a terrible hangover, previously unknown to me, is one of the most unpleasant feelings I can imagine.”