This is a really simple chest opening stretch that does the opposite of what we do to ourselves all day long by sitting and slouching. When you sit and slouch, you turn off your posterior chain that holds you up against gravity (basically your back muscles) and your anterior line like your pec muscles, as well as contract and shorten the anterior part of your shoulders.
By lifting up your chest and taking a big breath into your lungs, turning your palms to face forward and gently pull your shoulders back as shown, you can open and stretch your front line, as well as activate your posterior line. Hold this stretch for 15-60 seconds as often as you want during your work day and you can help combat the effects that sitting does to you all day every day!