Regardless of wealth, status, or genetics, around the age of forty, there is a psychological and physiological watershed between those who exercise regularly and those who do not.

Don't compare yourself to others; compare yourself to your past self.

Do you want to be able to stand up and sit down without a cane in old age?
Then start practicing weighted squats now.

Do you want to be able to carry a bag of fruit home in old age?
Then regularly walk around with dumbbells or other heavy objects now.

Do you want to be able to climb stairs in old age?
Now is the time to practice weighted lunges or simply climb more stairs.

The main goal of exercising in middle age should be to maintain independence and enjoy a higher quality of life in old age for a longer time.

Start exercising at 40; don't hesitate.