Your former school teachers die. At this point, I think the majority of mine is gone.
Your gum recedes, and there’s nothing you can do about it except to stop smoking. On a larger scale, your circulation gets worse because your erythrocytes become less elastic, for reasons still unknown. Add to this the most damaging impact of UV light and our atmosphere’s oxygen - an objectively very aggressive chemical - and you start shriveling, just withering away from the outside. Molecular bonds are simply getting broken faster than they get repaired. Your insides last a bit longer, but their days are numbered, too.
On the plus side, you’ll get to learn new words for body parts you didn’t even know you had.
Just wait until your first student dies