Use smartphone as a tool
Most people use smartphone to consume, like watching a movie or playing games.
But I want to argue you should use it as a tool.
This is how actually Steve Jobs envisioned when he first launched iPhone. A sophisticated device made to enhance your current life. Not to take over it.
Another reason is this, we can't win the battle by our mere will power. You have to subtract those Internet services that monetise your attention. (Twitter, Instagram, Buzzfeed).
And include more apps that helps you achieve a aim in your life. (Kindle App, Pocket App, KineMaster). Adding value to your existing life.
This means using your phone as means to another end, not as end in itself.