How do you come up with content for your website?

I think this is my biggest problem so far, haha
So much empty space, and those new themes have got so many ways (Boxes with fancy graphics, boxes with parallax images, tabs, modals, list goes on and on) to show off you content they make you want to implement each and every one of them! But I personally have great difficulty coming up with good content. I usually just go around other people's websites and "steal their ideas" - But I still kind of repeat myself over and over over multiple pages... Do you guys usually face this kind of a problem? How do you come up with extra content for your site?