But consistency is essential to that kind of coping.
One of my college psychology professors said the hardest thing for people to deal with is not knowing what to expect. That's why prisoners who were tortured or brainwashed were kept guessing and never knew when their captors would be nice or cruel to them.
Some conditions can be under control or in remission, only to flare up or return, and that can be much harder to deal with emotionally than more serious consistent things.
And it can do more harm than good to remind people that "at least" they had time when they felt better and they already know how to cope. Please don't say that to someone with a returning or worsening problem.