DAR ES SALAAM, Oct. 10 -- FOR many young Tanzanians, turning 30 is no longer simply another birthday. It is increasingly treated as an invisible deadline: by then, a person is expected to have secured stable employment, built a house, bought a car, started a business, married, had children and established a life that proves they have “made it.” Yet this checklist often says more about societys expectations than the varied realities of adulthood.

Family conversations, friendships and cultural traditions reinforce these expectations. Social media makes them more visible, filling screens with carefully selected photographs of cars, houses, weddings, holidays, businesses and professional achievements.

For young people whose prog...