I'm 70 next birthday and have been fit and active throughout life.
In earlier years, I did a lot of watersports (windsurfing, surfing, canoeing, etc.) and skied at least a couple of times a year until I had a serious accident six years ago. I also went swimming, played badminton, and various aerobics/gym activities on a regular basis.
Currently, I do a session at the gym each morning (Body Pump, Zumba/Shbam, gym circuits, yoga - 7 in total) with one rest day, plus general activities - walking, gardening, etc. I eat well and grow as much fruit and veg as I can, make my own bread and yogurt and cook from scratch. I don't buy cake, biscuits, crisps, sweets or alcohol but would have them if I'm out.
I've been fortunate with my health (so far). I'm slim-ish (BMI about 20.5) and not on any medication or needed to see a doctor for at least a couple of years. I do take a range of supplements and try to keep up to date on research into nutrition and longevity (Tim Spector, David Sinclair, etc.)
I feel great and have a busy life, which I see as all part of staying fit and healthy.