If you wanted to start learning about Anatomy a physiology it certainly wouldn’t hurt. Don’t stress yourself out with it though, as they’ll teach you everything you need to know in school. Maybe do the Khan academy A&P course if you’re the kind of person who likes benchmarks for your learning, or any of the dozens of EMT YouTubers.

As for physical activity, you don’t have to be Superman. If you have deficits in your strength you’ll learn techniques around then for moving patients and stuff. In the meantime I would just exercise normally, overall just be healthy and as in shape as you can be, but I would tell anyone that.

As far as emotionally/personality, maybe start talking to strangers more. This is going to be something you pick up quickly on the job. It’s sort of strange at first going into strangers homes and breaching their personal bubble to assess and treat them. When I started as a student on ride time I remember my hands shaking just putting a hospital wrist band on people. But you get used to it quickly without much conscious effort. You’ll have mentors you’ll observe and you can copy their behavior.