I walk on my own or with DH & combine with bird watching & an interest in fungi &, though I thought I'd hate group walking, have joined a Ramblers group for a bit of socialising & new & longer routes. I also go on free Walk London walks (from 1 -17miles, along green routes, 3x pa) for variety & to get to know the wider city better. Although very sorty when young, I rested on my laurels, have no self-discipline & hate macho gyms. Although I resisted American franchises, I tried women only Curves gyms which suited me really well & the regular gentle wxercise machines solved knee problems & built strength & flexibility. Then it closed & I haven't found anything else like it. I have a Jawbone Up tracker which got me going but doesn't rule me. I've tried contemporary dance & never thought I'd be rolling around on the floor at 70. We oldies padded our knees & hips with flannels. I'm often away so regular commitments to classes don't suit me. Walking isn't really enough as you need stretching & muscle building too. As others have said, start with what suits you in a small way, alone & with others who give you ideas, & see where it leads. Don't listen to people making judgements about fitbits etc nor to your own prejudices. I'm fighting a horror at going to anything under the patronising title, Ageing Creatively. Just do something & keep searching.
Misguided charlatans? - mediums
Sneaking away - goodbyes
Not going out - ageing