I lost a lot when I lost my dad. I guess one the biggest thing I've lost now is the possibility of shared experiences with him. I've lost the possibility of talking to him about stuff that I know he would have liked. Not big stuff, just small stuff that would have entertained him briefly.
His last few months were slow and he couldn't do what he wanted to do. He missed out on a lot of things that he would have enjoyed, even in that short time. It was immeasurably sad. What happened to my dad could happen to anybody.
I guess a good thing to do is stay healthy and live life as much as you can.