Saying no is not an easy thing to get used to. But, you can do it in a way that is loving, and that is not adversarial.
Changing your life so that it is more balanced will not happen over night. It will take some time to get used to cutting out activities that drain you. But, once you feel how wonderful it is to have control of your schedule, and to only engage in activities that feed your soul, it will become easier and easier!