the only thing I could say is: train your abs until you can feel them and isolate them. Great pre-bellyroll training are bodywaves and camels because you use the same muscles.

It's seriously just practicing. Some people find it easier to start laying on their back on the floor, some find it easier standing up in front of the mirror.

Isolate upper abs. Contract, release, contract, release, over and over until you can't anymore.
Isolate lower abs. Contract, release, contract, release, over and over.
Then once you can do all of that, THEN you practice top, bottom, top bottom.

If you get to where you can isolate each, it's great to do while driving. You'll notice right away if the rest of you goes up and down, or if your back is moving.

I notice when I try to put them together that my biggest problem is actually releasing the upper abs. They just want to stay there once I contract them. yeesh

trying it with a book on your abs helps give you some feedback about wether or not you're getting the up and down at the 2 ends.

Also, just to get a feel for the movement, do it sitting down and not sitting super up right. It'll be a lot easier to do the move and feel the muscles. Another thing that I do is "in, in, out, out" with my hands on my belly where it is "upper abs in, lower abs in, upper abs out, lower abs out." Once you get used to it, it flows.

I can do the move, but I'm not super fluid with it.

Once you can "separate" your belly into 2 halves you can start working on making that 4. Thinking of smaller pieces will help you gain more control and fluidity in your belly rolls. But until you can get at least an elementary belly roll going, don't worry about that.

It took me 4 months to just get a semblance of a roll going on, with a little bit of "cheating." It took me even longer (a year or more) to get a fluid belly roll going, and that's just in one direction (from down to up my belly roll still looks very elementary).

Some people can do them naturally, others struggle. There is nothing wrong with that... just be patient and keep practicing. Practice in every way that you can think of: lying, sitting, kneeling. Put your hands over your belly to feel the contractions and releases. Put objects over your belly while lying down to see how they move. Even do "cheater" belly rolls! Maybe you can't isolate your belly very much yet, but if you can get that lower contraction to work with the help of your glutes or that upper release to work with the help of your chest, you should do it, because those moves will help strengthen the muscles you do need for the belly roll. You will notice that with time, you will need to "cheat" less and less to get that belly wave going, and eventually you won't need help from your chest/ribcage or pelvis at all.

Don't forget to watch videos of others doing it, picture yourself doing it, look at pictures, etc. Having good anatomic awareness of what's happening will help tremendously... do not underestimate the power of your mind!

I'm just learning how to do belly rolls myself. I found this article on www.shira.net. Maybe this will help too.

www.shira.net/dear3-rolls.htm

Remember to be patient with yourself and your body. We'll both get this belly roll movement down!

Wishing you all the best.

i noticed that i got them while sitting, and it is now hard for me to keep my ribs in the lifted posture while i do it, so be careful not to develop that bad habit ^_^