I gave myself permission to take the day of not too long ago. It was approximately 22 days ago, but who is counting. What I have realized that when you skip one day, the habit is not so ingrained that you automatically resume. You have to stay on top of it. One day is not so bad, but it can be your excuse for missing more.
Many times your GREMLIN tells you that you already missed a day, you've messed up and you can't do it any because _________ (you fill in the blank), and you should just give it up. Ambitious goals like this are for the real achievers. You have to acknowledge your gremlin, quiet him or her, and then realize that you can do it. You must also acknowledge that there are bumps in the road, but it doesn't mean you stop driving. You either have to drive around them or take a new course.
Don't let missing a goal (or to do) a day, two, or twenty-two, take you off the course to your success. Take a breath, congratulate yourself for what you have done, acknowledge the bump in the road, figure out your course of action (not inaction), and start again!