I’m 61 and a Cat 1 mtb racer. I’m doing what you’re doing on rest days—“active recovery” which to me is light walks or hikes with my wife, something to stay active. I like walks or hikes as they are weight bearing and good for promoting bone density and coordination (the latter if on irregular ground). As for recovery rides after races or bigger training rides, they are under an hour, flat, and super easy.