I know you touched on it but the importance of consistent overload is paramount as well for strength and hypertrophy. 80 bags of cement won't cause adaptation unless it's a regular occurance.
Responding to both at once. Yes, lighthearted comment. You're right about adaptation. The point I'm trying to make is simple: building physical exertion into your daily life is the best way to retain strength, flexibility, health and mood as you age. The habits are easier to keep. Combine that with physical recreation and reasonable habits regarding food, drink, chemicals and rest.