I have read that self-discipline is like a muscle that you can work out, and I believe it. Start off by making a real effort at truly working this muscle for a few minutes. Exercising self-discipline completely for 10 minutes is worth much more than only half exercising it for 60.

I have found a lot of use in timers. It's gimmicky, but putting a timer on my phone, and telling myself I will do only one thing until it goes off really works for me.