Water finds level when you stop disturbing it. Something similar seems true of mood: leave a person genuinely unpressed for a few days, no deadline and no dread, and something lighter tends to surface on its own.
A natural state isn't a permanent one. Weather still happens. It means the thing you return to rather than the thing you have to manufacture.
Which makes a lot of the work subtraction. Not adding cheer, but noticing what's been sitting on the lid — the message you owe someone, the late-afternoon coffee, the tab you keep reopening.