Set alarms, for starting work, stopping work, lunch, end of lunch, etc. Keep strictly to the schedule. Block out your working hours on your calendars, both work

Set alarms, for starting work, stopping work, lunch, end of lunch, etc. Keep strictly to the schedule. Block out your working hours on your calendars, both work and personal. Set up things like Slack to automatically mark you as AFK outside working hours. Never use personal devices for work, or work devices for personal stuff. Basically create strict domain separation, to prevent this blending.