Place a rolled towel or pillow between you and the backrest of the chair for additional lumbar support. Make sure to position it at the curve of your back.
Place a seat cushion or folded throw blanket on the seat of your chair to sit on for added comfort.
If the armrests on your chair are too low, use an armrest pad or wrap a towel or something similar around them to allow you to rest your forearms and elbows.
Laptop:
Raise the monitor of the laptop by setting it on a box, books, a laptop stand, or anything else that is sturdy enough to bring the monitor up to eye level. Make sure that the monitor is an arm’s length away.
Use an external keyboard and mouse.
Breaks:
Take a break every 20 minutes for 20 seconds by looking 20 feet away.
Get up, move, and stretch every hour.
Feet:
Use a box or something similar to elevate your feet if your feet do not touch the ground when sitting on your chair.