There's a real tension in modern life between respecting rest and feeling like you're falling behind. Kennedy's point isn't about grinding yourself to exhaustion—it's about the difference between intentional downtime and the slow drift into passivity. A couch suggests sinking in, letting hours evaporate, waking up wondering where the day went. A tool, by contrast, is something you pick up with purpose.
The tricky part is that both rest and productivity feel equally urgent now. You need genuine recovery, but you also need to actually do things that matter to you—learn that skill, call that friend, work toward that goal. The quote cuts through the either-or thinking. It's not saying "never relax," but rather: when you're not actively resting, don't pretend you are. Notice the difference between choosing to decompress and mindlessly scrolling while feeling vaguely guilty about it.
What makes this still relevant is that time is perhaps the only truly non-renewable resource you have. You can earn more money, build more skills, start over in lots of ways. But time spent is gone. Using it as a tool means occasionally asking yourself: am I being intentional here, or just passing time? That awareness alone often shifts how you actually spend your hours.