What Lincoln grasps here is that enthusiasm isn't something you *maintain* through hardship—it's something you actively choose to keep, again and again, which is far harder than the popular reading suggests. Most people understand failure as a stepping stone, but they imagine themselves as stoic travelers, gritted teeth and all. Lincoln reminds us that the real test is whether you can arrive at your tenth failed business venture or rejected manuscript with the same spark you felt at your first attempt. A scientist I knew spent fifteen years on an experiment that consistently failed; what kept her going wasn't grim perseverance but genuine curiosity that each failure refreshed rather than depleted—that distinction between endurance and actual joy is what separates the people who succeed from those who merely refuse to quit.