I am 71 years of age, I don't consider myself as 'old' I think of myself as ' young at heart'.
I have lived a healthy lifestyle up to now, I like cycling, mainly in the summer months and go walks all year round, the walks during the winter months are longer than the summer ones. I also exercise at home, yoga I like as well, I plank regularly, my 'record' is 6 minutes doing the elbow plank and 5 minutes doing the full extended plank, however, I do a 3 minute one every morning, later I vary between doing 100 press ups doing 10 reps with, a minute rest and so on until I complete a hundred, that's two times a week.
Other days I do 100 sit-ups, this time its 15 with a two-minute break until 100 is reached, I also have two kettle weighs (5klos) not too heavy but I exercise with them as well.
I sort of regret having never done any serious running like doing 5k, 10k, half or full marathon runs at any time, I took up cycling instead. The trend nowadays is for many people to do those runs, I do watch them on TV and if there is a 10k near where I live a support the runners on the course.