The attached video demonstrates a yoga pose that I find very helpful – Baddha Konasana. I often relax into this pose prior to the start of my period, and during. The sandbags are not necessary to have a beneficial outcome (If you are flowing heavily, take care to pad yourself as needed) . While in the Baddha Konasana, I perform reiki on myself to balance my chakras, often focusing mostly on my 6th and 7th chakras. In addition to the pose, I release the spine with a twist.
You cannot do yoga. Yoga is your natural state. What you can do are yoga exercises, which may reveal to you where you are resisting your natural state.