If you could stop your body from deteriorating, then yes we could. See, we grow... grow... grow... peak, and then wither away (how lovely, lol). The physical plane is very limited. We live in it to learn, and one day we ascend from it to something greater (in my belief). It's not meant to be lived on forever, though I would love to watch millennia pass by! I suppose we do 'live' forever, but in many lives.
Though, I have heard that sharks could live for practically forever if they were not so prone to disease.