All I can say is, a lot. A LOT. Just coming out of a very severe episode, I'm deathly afraid to relapse. Maybe it will get easier at some point, I certainly hope so.

I think it would be meaningful if people here mentioned what their primary mental health issue is. As someone else has mentioned, the amount of energy needed to stay stable probably depends greatly on the issue you're dealing with.

In my case, my primary issue is bipolar disorder. Without meaning to be dismissive of other issues, I think chronic illnesses like that do require more energy to deal with than situational issues, like a one-off depression that's just completely "gone" at some point. Those will require a lot of energy to get over, but at some point you're "cured" and you can sort of relax. In the case of bipolar, it's never really gone and you always have to remain vigilant, you're always at risk of going into an episode, so you always have to take care to try and minimize the risk.