The findings of a recent study (Garcia-Valles et al. 2013) highlighted the idea that regular activity does not prolong life-span. On the other hand, it extends the health-span. They also reported that brain derived neurotrophic factors (BDNF) remain elevated in exercisers, as does mitochondrial activity (energy generators) in the muscles of exercisers. BDNF is important for neuroplasticity, that is, the biological ability to learn, feel and intellectually orchestrate new things, to lay down or modify neural pathways in the brain, in essence to possess a potential toward readily adaptable behaviour.
The authors concluded from their study that:
"life-long spontaneous exercise did not prolong longevity but prevented several signs of frailty (that is, decrease in strength, endurance and motor coordination). This improvement was accompanied by a significant increase in the mitochondrial biogenesis in skeletal muscle and in the cortical BDNF levels."
Movement builds quality of life through 'health span'.
Identify an activity that you simply enjoy - that way it is far more likely to be sustainable. You'll be less likely to get bored. Once it's established as a habit and you've accrued time doing it, the 'health span' effects will become obvious, and others will notice too.