One thing I do to keep myself from checking my phone every ten minutes is restrict myself from doing so until I've either written something or done something on my to do list. You can limit surfing to a certain amount of time, or you can do what I do and go through your social media sinkholes in a certain sequence and once you've gone through that sequence you stop until the next round after writing or completing tasks.

If you try it, let me know how it works for you.