I'm new here so I hope I'm not asking something already solved. I'm new to Mathematica and I need to manage lists created from files that usually spend a lot of time to be created. I noticed that saving and then re-opening the notebook basically remove the lists themselves, and I have to re-run the entire code every time, which is boring and a huge loss of time. Is there a way to avoid this issue and be ready to work on the notebook as soon as I open it?