You've probably heard the phrase - someone is talking about some course of events in their life, and they comment on how "It was all downhill from there really". Recently though, I've got a bit confused. Does this phrase mean to say:-

a.) Things got better, as going DOWN a hill is easier than going UP a hill

OR

b.) Things got worse, as, well...it's downhill, duh!
(These could also apply to the phrase "And It was all uphill from there really" in reverse).

I've heard the phrase used to describe both positive changes and negative changes - but what would you use it for? a.) or b.)?