Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.
The best architectures, requirements, and designs emerge from self-organizing teams.
If you want to be agile, you need to be Theory-Y.
* Theory-Y is often considered a “management theory”, but actually is more general than that. Theory-Y is a fundamental assumption about human behaviour – that says people are intrisicly motivated (rather than Theory-X, which says they are motivated by rewards and punishments).