Stand up and walk around for a few minutes
Get some fresh air
Drink water
Wash your face with cold water
Turn on bright lights
Stretch your body
Do a few quick exercises
Change your posture
Avoid lying down
Take a short nap if possible
Drink caffeine if appropriate
Eat a light, healthy snack
Avoid heavy meals
Reduce boredom by switching tasks
Listen to upbeat music
Keep your room cool
Open a window
Talk to someone
Break work into small tasks
Focus on active tasks instead of passive ones
Avoid alcohol and sedating medications
Get enough sleep later