Why can’t I stick to it?

I start off strong, I have worked out my protocol, I get to 3:30-4:00 and I get tempted.  I wait, I listen, I think it’s o.k. and I can start tomorrow.  Just like that, I break my protocol. I haven’t yet worked out my commitment.  Every time I set a commitment I break it and I get so frustrated with myself. How can I work out a rock solid commitment so I stay focused?