Some working days you are figuratively done with it at the end of the day. You can often prevent this dip by gaining new energy during the lunch break.
Eat healthy
Instead of a greasy bite, it is better to opt for a healthy and nutritious lunch. That is not only better for the line, it also ensures that you have more energy in the afternoon.
Go around the block
It's nice to take a break from your workplace and the computer for a while. Going for a walk outside will give your energy level a boost.
Have a chat
Chat with your colleagues, drop by someone from another department. That way you can blow off some steam and get back to work feeling refreshed.
Take short breaks
In addition to your lunch break, also take a few short breaks. Make a cup of tea, get coffee, go to the toilet or flip through a book. Short moments of distraction keep you sharper.