A couple of years ago I came across Wai Lana's Little Yogis DVD and Reuben fell in love with it, I had never heard of her but I gather she is a TV personality in North America with her yoga programme (and lover of colourful clothes and much make up).
I am recommending it because this is one of the most watched DVDs in the house! I have always practised yoga and Reuben used to do a little with me when he was a toddler, but having their own DVD they can stop and start as they please (with lots of cute children and nice songs and animations) has made the boys really motivated. We also have the yoga mat that goes with it so Reuben can practise on his own (and he does!!)
More information on Wai Lana can be found on her website
http://www.wailana.com as well as a huge range of yoga related products, this is a US website but we got the DVD from Amazon and the mat from YogaStudio
