Collect the following pieces of paper to increase your total health.

Castle (second floor), southeast.
Toasty Cave, last room, Fire Sword required.
Cave in Western Island, Fire Sword required.
Warped Woods, last room, Portal Wand required.
Cave in Eastern Island, Portal Wand required.
Castle (second floor), east, Fire Sword and Portal Wand required.
Castle (first floor), west, Fire Sword and Portal Wand required.
Castle (second Floor), southwest, Fire Sword and Portal Wand required.
That Cold Place, last room, Ice Wand required.
Cave in Swamp, Ice Wand required.
Castle (first floor), southwest, Fire Sword, Ice Wand, and Portal Wand required.
Castle (first floor), northeast, Fire Sword, Ice Wand, and Portal Wand required.