Activity Analysis will help you understand the different actions, interactions users have with a product or a service. This is necessary to create a blueprint for service design.
Ask yourself: "What are the steps?" (turn off the car, take out the key, open the tank with the key, hang the cap with the key attached, put your credit car...), "What are the artifacts?" (car, key, fuel pump, paying screen...), "What are the goals of this task?" (turn off the car, full the tank, be able to drive to your holiday place...) and "What are the pain points?" (the baby is crying in the car, my hands get dirty, the machine doesn't accept my credit card, my key is hanging down the tank cap...). Going into details, thinking about different situations of use will help you cover as many issues as possible and transform the pain points into good experiences.