I had been a life long cyclist, until I lost all my fitness by being unable to leave my mother on her own, (dementia); that cost me 8 years of near inactivity.
I haven't been able to regain my fitness to any reasonable level, & I just can't get up the hills or do the distances any more.
But, I used to go walking in the countryside too, & I can still do a bit of that, although not as far as I could before.