Ideas in the Middle of Writing a Story

I hope that I'm not alone in this: when you are in the middle of  writing a long and thoughtful story and then you get another idea, and then another, until you can't retain all of your ideas any longer. Isn't that annoying? What I do in this situation is just start writing the idea down- it doesn't matter if you are 2% finished with your story or 99% done, just start writing the idea down- and the moment you can't think of what to write next, go back to your original story. Of course, you could get a very mild case of writer's block in the first page and therefore can't get the plot going, well all you need to do is add a comment about everything that happens and then take the story from there when you are done or sick with the original story that you were writing on.

If you like this suggestion, please take it, but if you don't add ones that you do like in the comments below so other people can know other ideas.