Authors:

As long as my heart's still in it, I'll keep going. If the passion's there, why stop?... There'll likely be a point of diminishing returns, a point where my strength will begin to wane. Until then, I'll just keep plodding onward, putting one foot in front of the other to the best of my ability. Smiling the entire time.

Dean Karnazes (2006). “Ultramarathon Man: Confessions of an All-Night Runner”, p.199, Penguin
As long as my heart's still in it, I'll keep going. If the passion's there, why stop?... There'll likely be a point of diminishing returns, a point where my strength will begin to wane. Until then, I'll just keep