...it's frustrating as heck to feel that years of consistent working out have done nothing to improve my actual condition

Well, that's not entirely true. "Condition" is not a single, easily measured thing. Condition is task-dependent. As a demonstrative example - the conditioning one needs to run a fast sprint is not much like the conditioning needed to run a marathon.

You worked out for years - you conditioned your body for activity that's like those workouts you did. You did see improvement in muscle strength and cardiovascular health. I'd say you saw a decrease in the incidence and severity of upper respiratory infections.