This is embarrassing to admit, but for years, when people would talk about tracking calories, I interpreted it to mean that 1) they only ate in (as in at home), because 2) they would have to measure and weigh every ingredient that would go into every carefully crafted meal that they meticulously prepare to figure out the exact number of calories they're ingesting. I have no clue where that thought came from, but that was my idea of calorie counting. So when a colleague told me about a free calorie tracking website called My Fitness Pal, I told her I wasn't interested. After hearing enough people rave about it, I logged on to check out the website and instantly realized what a dunce I'd been. If you're not familiar with My Fitness Pal or calorie trackers in general, they are free websites with an extensive nutrition database and simple tools to help you track your daily caloric intake and exercises. I've found MFP to be very user friendly and easy to access. It's ridiculous that I didn't hear about it until mid-2011!
Once I downloaded the iPhone app, I no longer needed to write down what I had eaten or remember it until I could get to a computer. For me, logging as soon as I'm done with a meal or snack ensures that it gets tracked.
When you log in, MFP will tell you how many calories you have remaining (or the total number of calories you have for the day, if you're logging in for the first time that day). From the home page, you click on