The reason these problems exist is simple: we are socially rewarded for working long hours because it lets us say we are already helping other people and there is nothing more we can do.
This helps people we know, but hurts people we don't know since most of the problems of the world are due to a lack of money, which usually comes from paid work. We can change the social incentives to work more by affirming that we don't have any problems and don't need any help.
By supporting this petition, you can tell your friends that you want to help the Third World by giving those people jobs and knowledge, even if it increases the cost of gasoline through higher demand.
To fairly compensate for higher productivity when working less, businesses can give a higher wage rate when people do so on the condition they will work more when necessary. Example, 1.2x for the first 24 hours/week, 0.7x after that.
When unemployment decreases this way, wages go up but there is no inflation because people still look at prices. The money is just taken from the profits of luxury goods sellers like Louis Vuitton, the financial market, and even Apple.
This gives jobs to people in poor countries by increasing the demand for cheap products, especially if their wealthy people also stop buying foreign luxury goods.
No starvation in Africa.
No more consumption for the sake of consumption.
No need for military spending or wars as a jobs program.