fast-paced yoga: Ashtanga, Vinyasa, or

any flow-based yoga. One unique advantage I see in yoga (compared to other forms of exercise) is its mental challenge, that is, to stay still, whether it's holding a pose or it's resting and relaxing in savasana. It is probably more challenging for a lot of people to be still and to be conscious of our breathing and our body, especially in societies where people multi-task all the time (and with cell phones, ipads everywhere).