A regular yoga practice offers us:
Ease in our bodies by accepting our current reality and remembering that it all changes.
Ease in our breaths through intimate practices.
Ease in our minds with observation of the "pause between stimulus and response", as Viktor Frankl coined it.
Ease in our emotions as we search out equanimity between our most ruinous and elated feelings.
These are all wonderful benefits from the practice, but some may want more than experiential claims to "prove" why they should practice yoga.
Yoga Helps Side Effects
Most of the studies are restricted to observing the change in the side effects of treatment as the participant undergoes a regular yoga practice. In her blog post for the Mesothelioma Cancer Alliance, Community Program Coordinator Jackie Clark writes about 2 studies that show yoga helps manage treatment side effects for both breast cancer and prostate cancer patients.
Yoga Helps on a Cellular Level
A study published last November discussed how yoga and meditation helps keep telomere length (the bits at the end of the DNA strand) from eroding; longer telomeres have been associated with reduced genetic mutation, better treatment outcomes and longevity. The Canadian study suggests that meditation, yoga and support groups effected the participants on a genetic level.
People have been claiming that yoga helps prevent a cancer diagnosis, and this latest genetic link seems to point to that. I'm not sure that it's an easy link, though, because we are still dealing with the benefits listed at the start of this post... and those are not easily measured.