Be a catalyst
Think of your product or service as the catalyst or enabler of something in the life of customers and users. Describe their lives before your product (café, software, app, yoga pants) became part of their stories and then their lives after it. These before and after scenarios are important because they allow you to articulate the change that happens because your product exists. When you understand how the customer's story will unfold in the presence of your product and how that product helps to shape his new reality, then you can work backwards to the feelings that the features and functionality must create in order to move your customer from here to there.