A little over 2 months ago we released a paid version of Hevy. Since we're bootstrapped, we have exactly $0 to spend on marketing. We rely completely on organic downloads, from word of mouth or from people just browsing the App/Play Store. With that we manage to bring in about 50-80 new humans a day to Hevy. As of today 100 of those humans have decided that Hevy is worth paying for!
It's also worth noting that when we released Hevy Pro we gave all existing users free Pro accounts, so all of these 100 users signed up in the last 2 months.
I've never had a single person pay for anything I've built before so to have 100 people is absolutely staggering to me.