I wouldn’t be able to do that - I had to stop drinking caffeine a few years ago but still get cranky if I don’t have the experience of drinking a big mug of tea in the morning, despite the fact that the decaf tea has no direct pharmacological effect on me. Then whenever I’m bored or anxious or tired I make another big mug of decaf tea and feel better. It has to be tea; other beverages don’t help. Purely psychosomatic but still definitely a real effect.