If you spend Monday through Friday doing what you have to do and Saturday and Sunday doing what you enjoy, Sunday nights can be a real downer. Instead of getting anxious about going back to work, find ways to make the weekend last all week:
1. Find purpose. Work holds little worth if you don't believe what you do matters. Almost all organizations create some social value. Don't get lost in the humdrum; look up and remember that what you do has a purpose.
2. Stop the meaningless tasks. Mind-numbing activities can make work torturous. Look out for tasks that don't add value and stop doing them.
3. Keep it fun. Work doesn't have to be boring. Look for opportunities to engage in friendly competition or make your work more social.
Source: "Make the Weekend Last All Week" by Ron Ashkenas.