You may accept the number of candles on your birthday cake with grace and humor. After all, growing older is one of those facts of life you can't change, so keeping a good attitude is important. However, you may grow weary of the subtle comments about your age from co-workers.
Perhaps your younger colleagues assume you are not tech savvy because you are over 40. Maybe they never miss an opportunity to point out your graying hair or to make joking references about TV ads for products marketed to senior citizens. While you try to be a good sport about the jokes, it may be no laughing matter if your employer discriminates against you because of your age.