I have never been one for doing physical exercises - I can do pushups and situps , etc - but I don't really "enjoy" doing them. Doing things that are a definite aid to my personal functioning is however "justifiable" for me - to that end , after a thread in another NHS forum here, that discussed a supposed "longevity test" which involved a test of one's ability to get up off the floor - I kind of "invented" a simple exercise for myself to do. I simply lie down on the floor - on my back or stomach alternately - and then get back up to a standing position again, without any external aids. I can use arms, legs, hands, knees to do so - but no chair/table legs , etc .
Try this out some time and do say 10 repeats - you will see where I am coming from . It gets quite difficult and tiring and gets your heart racing - and the ability to get up off the floor is a very important ability to have as we age. I also suspect it is good strengthening exercise for our core muscles.