When you put yourself first it allows you to be the first one there to help when you are needed. Making sure you come first isn't selfish it's a necessity. In order to be there for others you have to have what you need including the proper rest. If you let yourself get overwhelmed without a break, you will breakdown. Then you will be unable to help anyone. It's nice to help others but you can't help till it hurts you. It's OK to say no. They would rather you say no when you just can't because they don't want to see you breakdown.