I've just turned 70, and my mid-50s wife can continue to do very financially rewarding three-month nursing contracts in the Australian outback as long as I stay healthy.
I do this through exercise, community engagement and a good diet.
I was put off lentils by The Young Ones TV program but my wife persuaded me to try gently cooking them with a mixture of frozen vegetables, some chopped leek and chopped-up chicken breasts, plus celery, thyme and sage for flavour.
Over winter I have been cooking this up in an old 1950s pressure cooker inherited from my parents. My own addition to my wife's recipe is to toss in the green leafy bits from top of the celery and the leek that I usually throw away.
A small glass of wine is a healthy addition. I hate wine glasses as they are so easy to break, so I use a little earthenware tumbler instead.
A strong incentive for staying healthy is that we now have a three-week "honeymoon" together after every three month contract.
Chicken lentils, wine and daily exercise is much more effective than Viagra.