Flexibility, strength and longer life

The November Discover magazine pg. 16 has an article discussing the above. The author found a relationship between the three. He equates the ease of sitting and standing unaided on a smooth floor with longevity. The more assists with hand or knee, forearm or thigh, the shorter the remaining life span.
I have been going in and out of seiza for 21 years because of the martial arts I practice.
BTW, I just turned 83.

Congratulations! I can't sit for very long like that. Meh.

Committing part of your life to tai chi strengthens body and mind!

Hm, interesting. do you got link for that article? i need to show it to my father

Yes, I'll link some stuff below.
http://www.treeoflifetaichi.com/Bone_Density.pdf
http://orthoinfo.aaos.org/topic.cfm?topic=A00674

If you feel you have nothing to live for, then your life is reduced. If you have something to live for, you have will.

I have been starting to train seriously again after my working overseas has ended and I have a lot of time and financial means again.

But sitting in seiza is hard for me... Mainly for my feet I don't know if it's a flexibility thing or my form is bad but I am hoping it will get better with practice, if anyone has any tips for making the progress more efficient please do share.

Another thing that really sucks is that after a hard leg day at the gym sitting in seiza is like grilling my hamstrings