Your heart probably won't get anymore efficient, and there's the lack of strength, but aside from that, good enough.
I myself treat my body very much like a beater car. Though I excercise and the diet isn't completely horrible, I haven't had a proper checkup in well over a decade, haven't been to a dentist equally as long, actually have some damaged molars that need fixing but are being ignored, I've had more than a few tendon related injuries that again, never bothered with a doctor. Eyeglasses I've had for 5 years, health insurance I got only because it was cheaper than eating the Obamacare fee but never used even preventative, nice cyst on my shoulder that was never looked at, etc, etc, etc. Don't ask about cancer screenings and family history btw.
I should know better than responding to a Naer thread, but I'm giving benefit of the doubt this once.