My first programming job was unionized and the hours were strictly from 8:30-4. With breaks, that worked out to be about 6-6.5 hours per day. I would leave wo

My first programming job was unionized and the hours were strictly from 8:30-4. With breaks, that worked out to be about 6-6.5 hours per day. I would leave work with lots of energy and be energized to start the next day. I left that job for another one but needed to work 1 hour more per day. It was a pretty similar office environment. I was amazed at how much just one hour a day changed my mood. After a few weeks I no longer had that energetic feeling anymore when leaving work or when waking up. If you're optimizing for happiness, I think a 30 hour work week is ideal. 10 hours a week is too little to feel happiness and fulfillment from that.