I’m in my early thirties and similarly learned French from 0 to a conversational level in a bit over a year. (Though I was already pretty strong in Spanish so that helped significantly)

The age thing is mostly a myth imo. If you put in the time and effort you’ll get a lot back.

The biggest issue is the concept of fluency. A lot of people believe they have to be 100% perfect or they don’t “know” the language. In reality, from the moment you start you will continually become more and more comfortable in an asymptotic manner (no one knows 100% of a language, ie what percentage words in the dictionary do you know).

The biggest piece of advice - get comfortable in dealing with ambiguity, and don’t try to force constructs from your primary language onto the one you are learning. Meaning: don’t say X word means Y word in my native language, therefore I can use it exactly the same (it’s a different word, VERY likely with different connotations).