Use your Past.
The value of yesterday is not in the "woulda, coulda, shoulda paradigm" of regret, but rather in learning how to be more effective. Using your past as your guide, how can you be even more effective today in realizing your intentions?
There is no such thing as a mistake. The worst thing that can happen is that you realize that you could have made a more effective choice given your intention. Sometimes, it is only the pain of the experience (the effect that we caused) that enables us to become clear about what we want to create in our lives. The key is not to repeat the same behavior expecting a different result (the true definition of "insanity").
Take some time today to examine the past couple of weeks. What can you learn from your experiences? If your life was a story, what would the moral of the story be thus far? How would you like for the story to unfold from this point forward? What can you do, beginning today, to begin living a more enjoyable story?
Success or sabotage? You are the author of your life. Be conscious of the plot as it is unfolding. If you don't like the direction, re-write it!
Is this going to be an incredible day? How can you make this day even better than yesterday?