Being good is too subjective. If you define good as hedonistic discipline; it can be very challenging. It does get easier over time to withhold pleasure seeking activity; dependence on dopamine release can be decreased with cessation and/or moderation. Cravings and need decrease when pleasure seeking activity is decreased. If by good you mean simply being kind to others, and not being a jerk; that's pretty easy with basic self control. Teach yourself to recognize your emotional responses and triggers, and regulate accordingly before speaking.