Actually aging is kind off preprogrammed.If ageing was pre-programmed it would be very easy to solve, but it's not. It's not a matter of opinion, there's experiments with millions of (ageing) fruit-flies where you can 10x the average starting lifespan by just postponing the age of reproduction. This means that the genes/epigenetic phenotypes for longevity are chosen and life span will gradually increase, with no upper limit. Ageing is completely malleable in other words.
Your DNA strands have a little end cap on them, and as you age, these degrade, allowing the DNA strand to decay.
Think of them like a shoelace, with the little plastic bits on the end keeping it together.
Everyones shoelace unravels at a different pace, but if we could just keep the end cap together it would be great.
But we cant do it for shoelaces let alone DNA yet.