Cynical take - if you know you're lying, that's not optimism, that's cynical manipulation.
A lot of people missing that cynicism isn't the same as sneering grumpiness.
You can be perfectly pleasant and charming while being utterly cynical about how you approach professional relationships.
This is a problem with at least two axes. The cynicism part relies on accurately calibrating the distance between official narratives and reality.
If you're a pessimist, you overshoot. An optimist undershoots. A realist gets it more or less right.
But if the distance is huge, that automatically makes the realist a cynic, because the reality is a lie, and in most orgs failing to take false narratives at face value is considered dissidence.
The strategic part depends on how you handle that. You can be sneering and negative, you can play the game with a fake smile and an eye for opportunity, or you can aim for neutrality and a certain amount of distance.
Sneering negativity is usually the least effective option, even when it's the most honest.
A realist in a functional organisation won't be cynical at all.