You still can use the same phone, uninstall all distractions from the phone. Use a computer to close all accounts. Keep either one or two media accounts only. Mute notifications from the media app which you decide to keep. Buy a wrist watch and use it for time. Avoid checking your phone. Set up a schedule on your phone which locks all apps during downtime. Personally I tried moving to a non smart phone due to banking and finance could not do so.