You are at work, that is a great achievement in my book - I couldn't work.
If you can, take regular breaks, go out of the office, out of the building if you can. Once out, look around, for once the weather is warm and sunny, feel the sun, look around, what can you see, rub your hand on a surface, how does it feel and breathe, count the breath, in four 4, hold for 2 and out for 4.
If you can't go out, sit in your chair with your feet on the floor, feel how you connect with the chair, do the breathing exercise.
And as for hating Mondays, sing it out with the Boontown Rats :whistling:.