Material things are things that exist independent of perception. The choice to get better is not a material entity, it does not and cannot exist independently of perception. The choice to get better is not material and therefore cannot be attributed to materialism.
Let's follow this through.
The choice to get better (or worse) is not material, true. But, what is it contingent upon? Choice is dependent upon options (having two logically distinct possibilites; two possibilities in which it is impossible to have both), making a decision and intelligence. Intelligence requires a brain. A brain requires Matter. (Unless you can show otherwise, which no one has yet.)
A rock does not choose to get better since it doen't have a brain. Likewise, Democracy, as an immaterial entity, does not choose to get better, since it has no brain and no Matter. (It requires matter, though, in which to exist, since otherwise it would be absurd - like claiming that sound can be red).
Can you name an immaterial item that has choice? Can you name an immaterial item that isn't contingent upon Matter?
Let's say, logic? Logic, maybe as a simple proposition that "a" cannot be "a" in the same time and place. If there is no matter, then this simply doesn't apply. (One reason Theists claim that their god can be logically inconsistent since it is immaterial).
Of course, we are dealing with accualities here and logic DOES apply in our universe.
I would be interested if you can show that immmaterial items would exist if there was no Matter. (Concepts are reliant on a mind to percieve them, a mind is reliant on matter).