Prompt: What Lit Up Their Spirit?

Your beloved had a unique spirit. That spirit responded to the world in its own unique way. 

What delighted your beloved? What gave their spirit a boost? What could they do and lose themselves in, perhaps not stopping for a stretch break or a drink until well past when they should have. 

Perhaps it was an action, or a concept, or a cause, or an item, or a [insert noun].

Maybe you couldn't really understand their interest (or obsession!), but you could see that it animated them when they became embroiled in it.

Maybe you weren't a fan of that thing, but you could appreciate their appreciation and could see what it brought to their lives (or maybe you couldn't, but there was no denying it lifted their spirit).

What did they do that might have looked like work or drudgery, did not get compensation, but felt happy doing it?

What lit up their spirit?