You really do care about your people and you don't want to come across as thoughtless just because you're in meetings all the time and forget to say anything when a member of your team has a 5-year anniversary or it's someone's birthday.
Just look at the 'Milestones' tab every once in a while. At the top you'll see three important areas: tabs for Birthdays, Anniversaries, and a scope dropdown. The scope is as follows:
The comments you make will be posted on the day of the anniversary or birthday. No more forgetting.