What if I don't want a close relationship with my dad?
That seems strange. Why don't you want to be close to your dad?
I do not enjoy listening to his complaining about his health.
Your dad probably needs someone to talk to. It's a good thing to be close to your father.
It's just that I can't stand him talking about it over and over.
Well if that is the only problem, just try to get him to talk about something else. And if that doesn't work then talk to him about it so he knows it bothers you. But you should keep working on it, it is good to have a good relationship with your dad, you might need his support later in life.