Saving animals is not for the faint of heart. The tireless - at times, seemingly futile - fight to stop poachers, deforestation and extinction requires unshakable optimism and is often paid with blood, sweat and tears. This week, we shine a light on that rare breed for whom no price is too high to save the planet. We talk to them about their lives, what drives them, what keeps them going, and the species closest to their hearts.