but ibrahima seck is committed to making it a reality.f people are in poor physical shape because they don't eat a healthy diet and get enough exercise. in 2014, over 10% of men worldwide were overweight and about 15% of women. the world health organization recommends at least 2.5 hours of physical activity a week. studies say those who do this outlive their more sedentary peers by an average of almost 3.5 years. reporter: they're not exactly the youngest women in the world -- but they want to stay in shape. i am meeting alita seitisho. she shows me her favorite exercise stations. alita is 59 years old -- and one of the youngest here. >> do i have to go slow or fast? >> no, i like it slowly. reporter: she tells us she likes the leg press. the women come here every evening after work. many are still wearing their work clothes. they have housekeeping jobs in the neighborhood and can't afford to go to a 'normal' commercial gym. alita seitisho: i can turn like i want. i can turn backwards, rightwards. nothing can happen to me, the way i feel.

reporter: ibrahima seck is an agricultural expert and a visionary.reat deal of his time in meckhÉ, a town in senegal. he's working to win people over to sustainable farming. much of that work involves peanuts. they're a traditional crop here in senegal. ibrahima seck: peanut farming was introduced by france when senegal was still a colony. peanuts were almost the only crop in the entire region. the impact of that was enormous. reporter: that was more than 100 years ago. even today, around half of all farmland in senegal is used to grow peanuts -- if they grow at all, that is. a century of monoculture has damaged the soil. the effects of soil erosion, loss of nutrients, and desertification are visible everywhere. local farmers say the soil is almost entirely depleted. plants can hardly take root anymore. ibrahima seck: peanut monoculture led to extreme soil degradation. a loss of biodiversity means a loss of natural resources. the soil, the water, trees, plant biomass -- it's all gone. reporter: the peanut harvest has suffered as a result. that's a ma