You will never have more energy or enthusiasm, hair, or brain cells than you have today.

In this wry, self-deprecating line, Magliozzi turns aging into a comic but pointed argument for urgency. By pairing intangible resources (energy, enthusiasm) with bodily markers of time (hair, brain cells), he suggests that both motivation and capacity tend to diminish rather than accumulate. The joke sharpens the underlying counsel: don’t postpone the things that require vigor, curiosity, or courage, because “later” is not a guaranteed upgrade. The humor also fits Magliozzi’s public persona—plainspoken, teasing, and practical—using laughter to make a memorable nudge toward action and appreciation of the present.