For me my motivation to learn differs per language. I'm from Northern Ireland, so learning Irish feels full of meaning, emotional, social and political... it's kind of bittersweet because I know so little of the language of the island I am from, I'm not patriotic or nationalist so don't feel like I'm doing it for those reasons, rather I haven't lived in Ireland for over 10 years now and this feels like a way of reconnecting with the place besides talking (in English) to my family members, and in this way I get a really positive and exciting feeling. I like to imagine myself back home one day and being able to talk to someone new in Irish and what that will feel like - connecting to deep roots while at the same time being fresh and new?
On the other hand learning Chinese began as a mid-pandemic "let's try something new" thing which I didn't plan for, probably didn't expect to stick at it, and instead it's become a window onto the other side of the planet, a widening of my horizons and understanding (totally different grammar, the characters rather than an alphabet - lots of things that take me completely out of my comfort zone of European languages) that I am finding surprisingly incredibly fun. Now I'm signing up for HSK 1, and fantasise about visiting China and being able to hold a conversation :)