The manner of our death seems to be one of those things not under our control:
QuoteLetter to Menoikeus, DL, X: 127: Remember that what will be is not completely within our control nor completely outside our control, so that we will not completely expect it to happen nor be completely disappointed if it does not happen.
That being said, we can exercise which may lead to a longer life. We can eat properly and drink alcohol moderately who may lead to a longer life. But there are no guarantees. However, if we live wisely, justly, and nobly, we will at least have a better chance of living a longer healthy life before we die.