I've never been on good terms with my father but one thing he taught me when I was young stuck with me through my teenage years. That you don't expect anything because expectations only leads to disappointments. That if you don't expect, you can never be disappointed.

Just because you visited someone when s/he is sick doesn't mean you'll get the same treatment. Just because you surprise someone doesn't mean you will even get a present for your birthday. Just because you put in your utmost effort doesn't mean you will get the same amount back.

But sometimes I can't help it. I can't help wishing I was treated fairly. But the world isn't fair. And I get disappointed all the time. 

Don't expect and you won't be disappointed.