What You'll Need
A straight bar and some weights on either end to act as wheels. Throw a mat down too, because we all love your knees, or not and tough it out.
Why You Should Be Doing This Exercise
This exercise is for those who are thinking, "Look, I don't have an ab wheel, but love the motion, so what have you got for me?" We've got this. Make the wheel yourselves. You're a resourceful bunch. How about a small barbell and a couple of 10 pound plates? Why bother? Because including the core benefits this exercise provides, it'll also help you with a number of movements.
On the mat, get down on your knees and place your hands shoulder width apart on the bar. Yeah, you're ready.
Slowly push that bar forward until your upper body is as close to the ground as you can go without touching. Your back may want to curve in to make this easier. One way to combat that is when you're rolling forward, your feet can go in the air (while your knees remain stationary).
Once fully extended, and without touching the ground with your upper body, slowly roll back out to your starting position. This won't be easy. It's not supposed to be. If you're doing it right, your upper body will remain nice and straight, and you'll be cursing OneResult for suggesting the exercise.
Focus on your abs stretching out as you roll forward. Don't fight that from happening. Also, don't collapse in a defeated heap when you're fully extended, because the goal is to not touch the floor. But you wouldn't think of doing that now would you?