Some time you cannot be what you want, Not every body can be an army, a doctor and astronaut. BUT you can create another jobs close to it. Eg somebody not fit to work in the field (river, forest, mountain, etc) cannot be an ecologist. May be the can be a modelling statistician, working closely to the ecologist.....many more jobs and fields can be created and adapted. That why we say democratisation of education to create and adapt to many challenging jobs in the future.