I think I just realized why all this middle-aged in your 30s nonsense bothers me so much. Ostensibly, I work in marketing now, and demographic lines must be drawn. Sure, there's squabbling between generational cutoffs (I swear Gen X/Y used to split at 1978 and now I see 1980 cited more and more) but once you make a rule you stick with it, no anecdotal squishiness.
That's why I was very pleased to see (not to read–even though I write this kind of stuff I wouldn't say that the ROI of customer experience is enjoyable reading, though if I could make it enjoyable there's probably money and glory to be had. I'm currently supposed to be writing about loyalty marketing using social media, er…) this article that neatly pegged middle-aged as 45-65, which is exactly how I would pigeonhole. After 65 you're a senior, below 45 you're just an adult. End of subject.