My cat is 11 years old and is in great health. She drinks a lot of water and eats well.
I don’t know why she whines so much.
I don’t play with her very often. Could she be bored?
She's definitely trying to communicate with you so try to figure out what she wants. If she's been fed, then she could just want some play time and attention. Think about a cat's world - not very big. So you should try to make it stimulating in some way. I had a cat who would sometimes come stare and me and I'd ask her what she wanted and to show me. I'd get up and she'd go to what she wanted. They train us!
Boredom or hunger are definitely 90%+ of whining, but it could be other things. You said great health, but sometimes its hard to tell; with an 11 y.o. cataracts or dementia are on the list.
Whining, to me, is definitely a sign of your cat trying to tell you something. Is this a recently new development? If so, what changes have transpired in your home before then?
When you say great health, is that based on a recent senior health checkup, including blood work? Aside from that, any other signs that there might be an issue besides being bored - eating, drinking, peeing/pooping normally?