Does increased physical activity increase the rate of cell division?
My understanding is that telomeres are linked to cell senescence, which is not necessarily the same thing as organism senescence. So even if you could track down a method to slow cell division, it would more likely mess with organ function now rather than extend life. 

Here's a nice summary of cell senescence: http://www.ncbi.nlm.nih.gov/books/NBK26877/#A3266

I did look into cell division in muscle, and new muscle cells come from satellite cells, rather than from mitotic division of currently active muscle cells.

Caloric restriction was the hot new way to live longer for a while, but studies in primates found that a sensible diet and good genetics have a bigger effect. Which is pretty much the T-shirt in medical science.

This question was asked last spring as well. Coincidence? Homework?