What is a one-sentence summary of the following article?
Usually, you will get a drain after surgery to suction off fluid. Some doctors prefer to remove it at a specified time, such as 2 days after surgery. However, it can reduce how much drainage you have overall if your doctor waits until your drainage levels drop below 20 milliliters (0.68  fl oz) per 24-hour period before removing the drain. That means you may need to wear it home instead of having it come out in the hospital. However, if your doctor gives you a choice, it can be the better option. Your body needs time to recover, which means no cleaning, gardening, or even dog-walking while you're recovering. You should wait until at least 3 days after your drain has been removed to resume normal activities. Otherwise, you risk increasing the amount of drainage from your mastectomy. Also, skip exercising and anything that requires you to lift your arm more than 90 degrees. While some studies have shown complete immobilization to be helpful, more doctors agree that just delaying shoulder exercises can be beneficial. It may reduce the overall drainage you experience. Talk to your doctor about this option. Usually, you perform shoulder exercises after surgery to increase mobility. Sitting up straight may seem like strange advice after surgery. However, slouching or hunching over can actually delay your recovery, which means more drainage overall.

Summary:
Wait to remove the drain. Rest your arm and body until 3 days after your drain is removed. Ask about delayed shoulder therapy. Work on your posture.