Not only move yourself from the chair, move your mind from work, but also give yourself a break to enjoy a moment with yourself when enjoying a cup of water, coffee or, of course, if possible, a cup of tea.
I know many offices have automatic coffee/tea machine but it does not offer you any pure and good taste, most of all it contains too much sugar and artificial flavors. At this moment, I strongly suggest Sugar-free and keep away from having too much sugar and/or sweet
Cold brew lightly fermented Oolong to boost your energy with some refreshing flavors and tastes can be a good choice in the warm afternoon.
Do some simple stretching