The unscaled version of the workout we post is designed to challenge someone in top physical condition. You are right - it is hard. Not everyone can complete the unscaled version of the workout. Some never will. But don't let that discourage you. Your goals will be different, your ability level will be different, and your experience will be different. CrossFit will improve your overall fitness and health regardless of your current fitness level (or even lack of fitness level!).
We post an intermediate and beginner version of each workout. This may still be too difficult for you. Don't worry - you can scale it further. First, check out these tips for scaling workouts. Then, watch the following video from crossfit.com that shows a workout being performed by four different athletes, whose fitness levels drastically differ: [mov][wmv].
Still think it's too hard for you? Check out this video of Barbara doing a CrossFit workout. Barbara is 73 years old and could not perform a squat, push-up, pull-up or sit-up when she began training. Now look at what she can do! All you need to do is be consistent and you will make progress.
CrossFit further demonstrates it's universal scalability by focusing on what you can do, not what you can't do. Take the example of the Warrior Transition Battalion from Brooke Army Medical Center if you need any more motivation! [mov] [wmv]
Now, stop worrying about what you can't do and give it a try! Here's how to begin...