As an older guy (50ish) I'm starting to take my health Very seriously and seeing my Doc as often.
An issue I've seen a couple of times is that we don't have a 'baseline' for certain tests. Ex: Testosterone and cognitive function. Getting tested now doesn't mean a lot, except on a loose sliding scale.
So! Younger guys, go! Get tested for "things". Then, as you age and get retested you have your personal baseline to compare your results!