Optimism is just a goal that we strive for. Just like any other goal, there are obstacles to overcome in the pursuit of it.
So there is tension, there is conflict, and there is struggle - even when you are on the path of optimism.
If optimism is the goal, you can deploy any tool in your arsenal to achieve it. It is not contradictory to be pragmatic in the pursuit of an ideal.
Likewise, optimism is definitely not passivity. Instead, it demands an active engagement with ideas, people, and everyday hurdles. You have to debate issues, you have to work to make things happen, and you have to watch your behaviour.
Rest assured you will not become boring for wanting a nicer world. You're not boring because you believe in idealised principles.
In fact, the pursuit of such goals probably are very lofty. That implies even more difficulties to overcome.
So rise up to the demands of holding a principled belief. Defend your ideas, actively engage in the world, and be rigorous against cruelty.
PS This sounds like the mistake that nice-guys make: thinking that blandness is the same as true kindness.