This article helped me understand it a little bit better:
I could not help but think of the excited feeling everyone gets on the weekend. Every Monday, everyone is forced to get up early for work. On Mondays, a lot of people carry an almost negative attitude due to the fact that they have a whole week ahead of them until they reach another weekend to do as they please. On Wednesdays, the average person gets over what has become known as the "hump day" , thanks in part to the talking camels from the commercials. For a lot of people, plans are being formed for the weekend which helps them find the motivation to work for two more days. On Thursdays, some people's excitement for the weekend is so overpowering that it has been nicknamed "Thirsty Thursday". Though many of these people tend to be younger adults that decide to add a night to their weekend, Thursday nights serve as a celebration of a final day until the weekend. After a final day of work, where most people seem to be in rather pleasant moods, the general public reaches the weekend.
Think about the feeling you get once you have completed your final responsibilities on a Friday afternoon? What about the feeling you get when you wake up on Saturday morning? I definitely wake up on Saturdays and Sundays much more refreshed than any other day of the week. I feel like on the weekend everyone is just generally happier since they have time to do the things they love. This creates the weekend mindset that everyone has developed from creating memories doing the things that they love.