Is it normal that people complain but refuse to try and change things?

There are very many people in my life that constantly complain about circumstances and then completely shoot down any reasonable option I give them. For example, if someone complains they are overweight and I offer to help them work out, they deny the help but continue to complain.

Is this type of behaviour normal?! If you don't like something in your life then change it! Don't sit around and feel sorry for yourself, do something! It just frustrates me so much! Another example is my sister lost her job about a year back and because she hasn't found anything in her field she refuses to work. Why doesn't she take up a different job while actively searching for something in her field? She complains about having to live at home and that she's broke, but just find a job! Any job will do at this point!

Are all people full of this much self-pity? I got frustrated with someone a while back and told them if they weren't willing to change then don't complain. They got mad at me and told me I don't understand. The thing is, I do! I was not the person I am today. I complained a lot when I was in high school about who I was. But one day I realized that I could just change it, because it was a hell of a lot better than moping around.