My motivation is trying to help the Fediverse grow and knowing it needs posters.

I try to post in most communities I'm in, although there's a few where I am incredibly new or my interest in the topic is super casual and I'm just an onlooker watching something I really don't belong to. In those cases I just sit back and consume the mod's content because I really have nothing to offer besides maybe a private message amounting to "I see your effort, thank you".