1) What is it you wish you were doing instead? Would you rather do that than looking at your screen? If so, it's a simple matter of prioritization. Find the will power to put down your screen and go do what you want. Once you start feeling the reward of that activity, it will get easier over time to prioritize that.
2) Are you addicted to your screen? Like you can't put your phone down for 30 seconds. If so, this might be a classic addiction. Addiction to drugs, alcohol, or even screens is about escaping from your pain. Seriously consider what happens in your mind. If you want to try an experiment, try doing nothing for 30 minutes and see where your brain goes. If something concerning comes up here, consider seeking help from a therapist. I'm glad to chat with you as well.
If I'm in the phase of design I take a notepad and go outside with it.
Undertake some projects around the house, for example.
Start a garden, do little wood working projects, smith some knives. Whatever tickles your fancy.