Well, ideally people could choose to do whatever they liked to provide for society. Everyone would have a role to play. So those that like to farm (raised on a farm, to be proud of their work) would farm, those that want to commit their life to science could attempt to advance their field. Someone might find an invigorating pride in making sure wastewater treatment is running well, but they don't know how to get into the field and are stuck working a job they don't like for money, currently. Artists could create culture. As long as you are doing something to provide for society, society will provide for you.

There will be people that do not have favorite hobbies. There will be people with no ambition who benefit from being told what they can or should do to contribute. Those people, in order to have their needs met could choose to take on a Necessary Task, even if it isn't their favorite thing. Maybe they learn to love it and excel at it.

Don't want to do anything to contribute to society despite being physically and mentally able? No needs met. Meet them yourself, you magnificent lone wolf. Want your needs met but don't want to do Necessary Task that you hate? Find a purpose and pursue it.