“But what if it's not SUPPOSED to be fun?”
That's a good and totally valid question. If you're working for justice, or saying hi to some inner demons, there are times when it's not going to be fun. And the point of life isn't happiness, but these activities are meaningful. You don't necessarily need to make your political app fun to get people into it. You need to make it meaningful.
Broccoli isn't sweet, but it's flavorful.
Your job as a designer is to stay connected to the meaning of your activity and help your practitioners do the same. You don't need to make it “fun” if it's not inherently fun.
When you try and twist your thing into something it's not, it seems disingenuous. And it misaligns your audience’s motivation. They think, “oh! I want to do this fun thing! Ugh. I guess I have to do some social justice first.”
That's not good in the long run.
When you're connected to the why, your activists think, “Hell yeah, today I'm gonna take one small step towards freedom. Let's make a fucking phone call.”
Find the reason, find the meaning, find the why, whatever that may be - and stay on it.
May you have a meaningful, free, and peaceful weekend,