Workout - Straining muscles just a little to encourage growth.
Chilling - No stress, no strain, everything kinda stays the same. But still have daily life strain, gravity, etc.
Pigging Out - Carbs, Carbs, no protein at all! Might encourage faster muscle degradation as the body isn't using ketones, so muscles could get metabolized faster
Space - Low gravity environments destroy muscles aggressively!
So I would posit - Spacing out is the opposite of Working out, and Pigging Out is a modifier bonus action.