Keep progressing and upgrading your town hall and you will eventually unlock it, aside that you can increase the maximum/reduce consumption of their Mood,Satiety and stamina via secret tech books. don't sweat it too much. later you will forget about it. since you don't have fountain of life you're still early game am guessing. later when you unlock 3rd class. one of your rangers make him Minstrel. and he will rejuvenate HP,Satiety & mood to nearby hunters. (message me if you have questions, since we're entering the domain of gameplay instead of hacking lol)