Delete all social media, install something like Cold Turkey (FOSS alternatives might excist but just werked for me), if you've got the means for it try to move on productive stuff you can do on your phone to dedicated devices (e.g. e-reader for reading instead of a reader app that your phone will eventually distract you from anyway). Ideally get a dumbphone.
Plan your day around more productive activities and a healthy sleep schedule and try to stick to your planning. Make sure to stay hygienic, well-groomed, dressed (even when unnecessary), healthy and preferably fit.>>6487
WiFi idea is not doable for a lot of people but worth considering if you can afford to.