James Clear, Lifehacker:
Learning how to say no is one of the most useful skills you can develop, especially when it comes to living a more productive and healthy life. Saying no to unnecessary commitments can give you the time you need to recover and rejuvenate. Saying no to daily distractions can give you the space you need to focus on what is important to you. And saying no to temptation can help you stay on track and achieve your health goals.
Clear goes on to discuss recent research that shows the powerful difference between “I can’t” and “I don’t” when deciding to say no.