Adjusting Your Chair
Fixed-height armrests are generally too low, encouraging you to slump down to them. Adjustable-height armrests are usually shorter and will let you get close enough to your desk while offering valuable support taking some of the weight off of your arms, shoulder, and neck muscles.
Short but fixed armrests can be raised by wrapping foam around them, or by adding a layer of foam and wrapping fabric around them. Don't be surprised if you need to add up to three inches of height in order to have elbow support when sitting upright.