Download every documentation you might need;
Delete every offline-capable time-waster from all your devices;
Remove your phone's SIM card (don't worry, you'll still be able to make emergency calls if such a need arises);
Unplug your internet router (and store it away somewhere inconvenient).
If you have to sync for any reason, go to a expensive coffee shop or the like that has WiFi and do your business there. You'll soon stop going so frequently because it'll hurt on the pocket.