Whilst walking fast to the hairdresser, took a superwoman pearler in the High St, tripping on uneven paving. Hobbled to hairdresser, where pub next door supplied ice to a rapidly swelling right knee. Agony next day, so to local hospital for x-ray (no damage) and crutches - bliss! Although I do 40 minutes cardio and 40 minutes weight training particularly for my arms and shoulders, twice a week, my arms were in agony after 2 days with crutches, when I was permitted to weight-bear again. My rehab has been speedy and appropriate (I'm a Pilates instructor, aged 65), and made me realise all over again the importance of exercise. Along with gym visits, I walk for an hour each day, and do half an hour of Pilates exercises, so fitter than average.
After reading posts, some suggestions. By the way, I have been known as "the nagger." There is no way of avoiding exercise, which some are trying to persuade doctors to prescribe, as it is really, really important, along with the healthy eating and active stress management to have an enjoyable old age, as you are all very well aware. Trying to break down poor habits is hell, I know.
So, ability and strength to get up and down off the floor vital, and a proper Pilates class will easily accommodate anyone struggling with this. Try to find hills to walk up, to work your cardiovascular system to a state of puffing. Dancing to your music at home is a great way to work up some puff, and use different muscles. That's the concern with osteoporosis and just walking, as there is no weight-bearing of shoulder girdle, elbows and wrists, the latter being particularly vulnerable in a fall. So press-ups need to be added - these can be done against the wall, as well as many other modifications. That's why weight training in the gym is particularly useful. And, by the way, we all eventually get osteoporosis, if we live long enough.