Better familiarize yourself with the concept of még and már since it's not English at all.
The implication with már and még is always that there has been or will be a change in the situation. So far this is like English. And here comes the easy part to be honest: in Hungarian: még simply implies the change is yet to happen and már implies it has happened already. And noone cares whether the change was positive or negative.
Már sétálok - I didn't use to walk but now I walk
Már nem sétálok - I used to walk but now I don't walk
Még sétálok - Now I walk but later I won't
Még nem sétálok - Now I don't walk but later I will
Még surely has other meanings as well (one is actually like "more" as in "I want 3 more apples") but for yet-not yet-already-no more kinda scenarios, these are the basics.