Braingym exercises can help enormously with getting the two hemispheres of the brain working together. I also believe (not backed up by any reading) that dancing with your kids can help - esp if they copy your moves and you do daggy mum-disco moves that include moving arms and legs across the middle of your body, as well as up and down. FWIW I did bellydancing for many years and it's surprising how many people are not able to repeat movements on opposites sides - but once you get them doing the basic cross-over moves they find the other stuff much easier.