Practical exercise to gain DDD experience when you don't have an Eric Evans at work. Step 1: model a domain you use daily (e.g. Uber taxi — ordering a ride). Step 2: wait for a new feature (e.g. Uber-based package delivery advertised as '90-minute shipping') and reassess your model. You didn't shape the domain, so you react to its real changes — a stress test for decoupling (don't couple 'ride' to 'passenger' so tightly that the only way to support packages is 'class Package extends Passenger').