Most likely HCM (hypertrophic cardiomyopathy) - it usually presents as sudden death/cardiac arrest during physical activity in adolescents

I haven’t looked at polish specifically, but I’ve had success with practicing languages on discord servers for language. If you check disboard for language servers, the large ones have plenty of people who want to practice

A little cheesy, but in middle school we read this essay called “Give!” By Anne Frank

How lovely to think that no one need wait a moment; we can start now, start slowly changing the world! How lovely that everyone, great and small, can make their contribution toward introducing justice straight away

Her excitement is what always stuck with me