what do you think your partner needs to change to make your relationship a better place?

Take care of himself better, because I don't want to have to feel worried that he's not healthy or productive... and I will naturally worry because I love him so much. He's perfect in that I never worry about if he's cheating or when he'll call, or if I'll have his protection and comfort, but I worry that he doesn't take care of his health and I wouldn't want to lose him down the line to some preventable disease or problem.

If you love someone then you accept them as they are, you don't expect them to change. If someone is expecting their partner to change then they don't love their partner, they love what they want their partner to be.