Many diet and fitness experts, even my favorite running coach, advise keeping a health journal to log your daily food intake and exercise. Tracking your daily regimen helps you see the gaps, problems and successes, plus your journal can help you stay motivated on your personal journeys.
I've kept one on and off, and noticed that I do much better on my training or weight management program if I stick with it. Plus, I can track my own trendlines - find consistencies in when I fall off the wagon and determine the contributing factors.