And I'd prefer to have the same stamina that I had when I was nineteen, too. I mean, it'd be cool if I could get absolutely smashed, and be fine the next day. I'm sure my SO would like it if I had the same stamina in the bedroom, too. I can't and I don't. There's a natural progression when it comes to a career, and being involved with managing other people is a part of that.
I'd probably ask about what my new job duties would be, and see if they fit with my desires, otherwise, it's a shot in the dark as to whether to take the job, fight to keep your current position, or find a new employer.
And be willing to accept whatever trade-offs come with it? That includes salary stagnation, and competition with younger people who might be more intellectually curious than you are, and expect a much smaller salary than you do.
One of the things that constantly bothers me when interviewing older workers is the fact that, in many ways, tech is no longer a joy....it's all job. I've found myself in that position more and more as I get older; building a Linux kernel is now tedious instead of exciting. I haven't had a GNU/Hurd install in years.
Interviewed a CCNA one time; when I asked him some questions about IPv6, he got defensive, then tried to convince me that it was never going to happen, and anyone looking at it was wasting his time.....
Needless to say, we had requirements from the customer for IPv6 work, and were trying to put together a team to address the project. Ended up hiring a 24 year-old without a degree or a cert, who was genuinely interested in where the technology is headed. Oh, and he wanted 60% of the salary (even without the military retirement, which the old guy had coming in, too.).