I recommend doing this work first thing in the morning and right before bed. Naturally if you find time throughout the day then go for it. Note: some people experience dizziness when starting a breath work practice, so I recommend lying down on the floor.
Lie down, bend the knees and use a pillow under the head if you need additional support
Close your eyes
Place one hand on the abdomen, place the other on the chest
Inhale slowly, allowing the belly to expand like a balloon
Exhale slowly with pursed lips - it should take 6-8 counts to full exhale. The back should flatten to the floor
Repeat 5 times working up to 10 as your practice improves.
Roll to the side, sit up slowly and then stand. Take a moment to just relax, then move into your day or hit the hay.
Breathing in this matter will be an exercise of reset and it will also strengthen the function of your diaphragm and lungs. The quote "just breathe" truly has a deeper meaning.