1. Don't wear reading glasses. They used to be called "granny" glasses for a reason. Even if you cannot see something, that's way better than putting on reading glasses.
2. When people are talking about something being for an "older group or >50" seem just as puzzled as to what those ancient individuals could be like, don't offer any insights.
3. When the kids mention their parents' ages and it is way younger than you, just nod. You may even be younger than their grandparents.
4. Keep pics of your kids on your desk from when they were under 5 so their ages won't give away your age. Most of your co-workers are probably now younger than your kids.
5. When anyone mentions what they are doing over the weekend, don't let on that you are visiting the kids (or grandkids), taking naps, etc. Just say something about Dumbo/Brooklyn and they'll all nod.
6. Never shut off. Routinely send unimportant emails, texts, even phone calls late at night, early in the morning and weekend. Nothing says old more than not being willing to be on-call 24/7.
7. Scrub your reference points. Don't mention movies or plays or even music that are older than three-weeks. Mentioning "Citizen Kane," and you might as well be wearing the mark of Cain.