You can do anything, but not everything.

This maxim is associated with David Allen’s productivity methodology (Getting Things Done), where he emphasizes clarifying commitments and making conscious choices about what to do—and what not to do. It is typically invoked in discussions of workload, priorities, and the limits of time and attention: a person may be capable of many different actions (“anything”), but cannot pursue all possible actions simultaneously (“not everything”). Allen uses such framing to encourage capturing commitments, defining next actions, and renegotiating obligations rather than relying on stress-driven overcommitment. The line circulates widely in productivity talks, summaries, and quotations attributed to Allen, often as a shorthand for the necessity of prioritization.

The aphorism distinguishes possibility from capacity. “Anything” signals that, given enough focus and time, a person can accomplish a wide range of goals; “not everything” insists that time, energy, and attention are finite, so attempting to pursue all options simultaneously guarantees dilution and stress. The quote functions as a corrective to perfectionism and overcommitment: productivity is less about doing more and more about choosing. In GTD terms, it supports the practice of defining next actions and outcomes while also maintaining a “Someday/Maybe” list—honoring ambitions without pretending they can all be executed now. Its significance lies in reframing limitation as a strategic tool for clarity and effectiveness.