How does life treat you when you get old?

Hi, I am 30 year old and this question is for Indians who are above 50. I want to know how does life get at that point. I am not too old but not too young. I think all the fun lies in younger age, and it’s miserable as you get older. Is my belief true? What about sex life? Does it get bad with age? Do you get lonelier being married in Indian society?