Come to the verge of doing The thing you like the most and just don't do it. This will work as a Reference Point in later life when you are tempted to do something unproductive. If you could give up that, you can easily give up this.
eg. If you like ice cream very much, take it but don't eat it...melt it with your hard stare infact ;)
Next time when you have urge to eat something unhealthy, recall the ice cream reference point which was much higher a challenge and #justdontdoit :)
Over period of time you will build enough reference points to avoid most distractions and temptations and can focus on things that matter most to you