Age doesnt matter too much. What matters is your current biology and health.

Like an obese 20 y.o who gets out of breath walking up the stairs, has high blood pressure and may die of a heart attack is not doing better than a 40 y.o who is fit healthy and not on the brink of death. As it stands the 40 y.o will live longer than the 20

So your biology matters more than your age, but, age does correlate with your biology so its helpful to keep track of it :)

Like if a women wants to have multiple children, she should track her age as after around 35 or so it gets harder to have children especially if she wanted many.