Today's challenge is to find something that has fallen by the way side (like my challenges over the last week) and get it started again.
It could be something as common as a diet that you have let falter or an exercise regimen that you felt to be too rigorous.
Maybe there is a project at work/school that you have been putting off because it too difficult (or too easy). Stop making excuses to yourself and start on it today. Don't leave today until you make significant and measurable progress towards completing that project.
Tomorrow you will have to continue to challenge yourself to work on this until you get back in the habit of focusing on it each and every day.