On my mother’s 90th birthday, I come off my bike on the ice. That has nothing to do with language learning, I realize, but at the Mum’s birthday party I meet an aunt aged 88 who does speak about that topic.
Her husband, Mum’s brother, was a typical Dutchman (of that generation). He’d controlled everything. He ‘drove’ the household. After he died, my aunt had had to fend for herself. Develop a social circle. Learn new skills.
She learned, or improved, her English by keeping a diary. She credits that habit with having mastered English after the age of 70.