iTutor Biology Updates

We've all heard it said, 'we start dying as soon as we are born.' True or false, half truth, old wives' tale, religious belief, nonsense? Myself, I've always thought that if I started dying at the moment I was born then why didn't the path to death begin at the moment of conception? I could never figure out the difference. IMHO I think that at some point as I age, the corner is turned and I head down towards the end of the road. I suppose aging could be considered as a good reason to think that I'm traveling in death's direction, inevitably I'm going to die because of it. But am I really dying if I'm growing while aging? Perhaps there is some scientific definition of dying that I've never heard of that would make sense, maybe. No doubt there are biological markers or clues that indicate you're not immortal. I've read of mitochondria providing evidence for the beginning of the dying process as well as indications associated with our own DNA. Would be nice if someone could explain those apparent signs to us laymen or if there are other things biologists deem worthy for discussing.